This was a bit of off-the-cuff, but I wonder if there should be a few more uses for Tactics, or the re-rolls granted by virtue of a successful Tactics contest, in GURPS. Tactics seems like it should do more, to me, anyway.

Things like:

  • Make a Tactics roll to get the benefit of partial cover when doing a retreating Dodge and Drop vs. an explosion. This would be to get the benefit of micro-environmental cover (that six to eight inch wave in the ground? Find it!) where such exists.
  • I wonder if you could use re-roll points to declare a Wait-and-Move on your turn. Basically, represent outguessing the enemy’s actions by letting him move first, then adjusting accordingly – even interrupting his move. He rushes you? You were waiting, and can move away.
  • As combat starts, when setting the turn order, look up your margin of success on a Tactics roll on the Size (and Speed/Range) Table. Make the Tactics roll by 5? You get +2 to your Speed for the purpose of setting initial turn order.
What other uses of Tactics (or Evaluate, for that matter) have you played with in your GURPS games?

So, it’s two weeks post-op. The procedure apparently went as well as it could go, I guess – information hasn’t been terribly forthcoming. They put in five surgical stainless screws (the phrase “living tissue over metal endoskeleton?” Yeah, it’s come up.) to affix the broken pieces of the calcaneus (heel bone) back together.

Key questions I had sorta-answered today:

  • It will be another month before I am to start weight-bearing exercises, and I expect those to be light
  • Real activity must wait until three months post-op
  • Full remodeling can take as much as a year
  • I can expect to develop arthritis in the area in a bad way, likely leading to a bone fusion later in life. This cannot be good. 

A lot of orthopedics seems to be a bit of a bailing wire and duct tape approach – we’ll “fix” it now, but you’re going to have to come back for even more surgery later. Sorry about that. They’re very cagey about what activities I can do or not do, probably for liability reasons.

I ran into that when I blew out a few discs in my neck, too. Asking about martial arts after rehab was over, the answers were all wishy-washy. Look, just tell me the risks and percentages, and I’ll make the call. I get that.

So. Back to the heel.

The incision was revealed for the first time for me. I forgot to take a picture of it, and now it’s under steri-strips. But it’s wide. I mean like 1/4″ wide. I think they actually made a 3″ long, 1/4″ wide U-shaped incision and peeled back the skin, to give maximum access. There’s another smaller incision, this one much more precise, a bit farther away. I suspect that was just to put in one more screw.

The swelling is down, believe it or not, and now that I can access the foot directly, I can massage the not-cut-on bits to help move some of that dried blood out of there. The ability to rub your own feet? That’s a surprisingly important thing.

I’ve been given mobility exercises for the ankle, too. Up/down motions, a few times per day, as well as side to side and inside/outside circles. I should probably do them about three times per day, which I will do.

The Boot, The Boot, the Boot is on fire

They’ve put me in a “fracture boot” for the next month. As noted in a prior comment (perhaps on facebook), I thought before that surely nothing could be worse than the cast in term of comfort.

I was wrong.

This thing is awful.

Now, bear in mind, for its intended purpose, which is a walking boot, it’s probably the right thing. But also bear in mind that I’m not allowed to bear weight on my foot for another 1-2 months. The boot, in my case, has three design goals

  • Keep the foot at a right angle
  • Be removable to allow me to do my mobility exercises
  • Protect the heel from incidental contact
So basically, it’s a rigid deflector shield that needs to come on and off.
In exchange for these things, what are the issues?
  • It’s much, much larger than the cast it replaced. This doesn’t seem like much. Until you bump it into things because your foot is now the outer dimensions of a shoebox. Or you try and get into a car, and can’t maneuver the foot into the driver’s side.
  • It’s much heavier than the cast it replaced. This manifests in some subtle ways. When crutching, one has to be very conscious of where it is, or else it’ll bounce on the ground, upset your momentum, and throw you to the floor. When sleeping – or more properly, making a futile attempt at sleep, the vast weight and bulk of this thing is like always being put in a joint lock. It twists your knee either to the inside or outside, and it’s very difficult to get to sleep. When sleeping, if you shift, the inertia of this concrete block can cause some surprisingly painful yanks. Which of course, wakes you up.
  • It is surprisingly hard to adjust to fit. This thing is a monster, but that’s not all. Once you force your heel into the bottom of the thing, it’s a rather involved procedure to get it put back together. First you have to work (ow) to push your heel into the bottom of the boot. Then you fold up a few padded flaps in the toe. Then you put on the outer plastic shell – but careful! The lower part goes inside the strap, the upper goes outside, and then you reach down to secure the three velcro straps. Then you have to inflate the thing in four different tubes. 
Again, what do I need? I need protection, the correct angle, and the ability to remove it.
This is clearly a case of “we have a million of these boots, so we’re going to use them.”
So I’m going to put my cosplay skills to use. I will probably whip something up with Aquaplast, but I’ll want to find larger sheets than 9×12″ for my needs. I suspect two sheets of 12×24″ would be about right. 
I’ll cut top and bottom pieces using a paper blank modeled from my good leg, but mirrored. Then probably mold them over my body, and then attach some padding on the inside, and velcro straps from the outside. It’ll give me removability, keep the foot at 90 degrees, and with the padding, it’ll stand off the heel by the size of the pad, providing both rigid protection and some shock absorbing capability.
And since the boot I’m wearing is already putting my foot to sleep because it’s too tight on the arch . . . this can’t come too soon.
They, of course, wouldn’t approve for liability reasons. A pox on their house – I need to sleep, and the boot is ridiculously overdesigned for the purpose I need it for over the next 4-8 weeks. The splint will be lighter, more convenient, and serve the needs better.
I end with more pix of the foot.

I promise I’ll let this go at some point. But not today.

In my little mishap from this past Tuesday, I estimate that I got tossed about 6-8 feet. 

Well. That’s enough to calculate a trajectory!

If we assume that I was launched at the most effective and efficient launch angle of 45 degrees for simplicity, that means that my initial velocity imparted by the explosion was something like 4.3m/s.

If we treat the Gaming Ballistic author as a spherical frictionless brainless cow massing 81 kg, we can see that the blast imparted to me roughly 350 kg-m/s of momentum and 750J of energy. That’s about the same energy as in a 10mmAuto, for comparison, but far more momentum.

Let’s assume that the combustion/explosion took place over a roughly 0.005 second period (5 milliseconds). That seems to be on the order of what some brief searching shows is on the upper end of how long it takes for the fuel-air mixture in an automobile cylinder to combust.

If that’s the case, it means that since Impulse = Momentum (F x delta t) = MV, that I was thrown with roughly 70,000 N of force! Roughly seven tons.

Is that reasonable? If half my body was exposed to the blast, that’s about 0.8 square meters. So a pressure requirement of 70,000N per 0.8 square meters, or 87,500 Pascals – 0.85 atmospheres.

According to the Wiki page on blast overpressure, 85 kPa is more than enough to cause severe heart and lung damage, and rip off limbs. Since that didn’t happen, my estimate is off somewhere. 

I suspect that the real problem is my estimation of initial velocity, since my mass is what it is. But I did travel that far (I measured!), so we’ll leave it as is.

It could also be that the velocity was fine, but if the overpressure effect lasted for much longer than 5ms. The force would drop by at least an order of magnitude, and the overpressure is lower and more in the “not turned to instant pulp” zone. Since I’m sitting here typing, that seems much more reasonable, and a discussion here of typical results and levels of overpressure suggest that since my house did not suffer any major damage (nor did I, really), that I was probably subjected to 0.04 to 0.4 psi of overpressure – let’s assume 0.3, giving me more credit for robustness and getting lucky a bit.

So that’s more like 2.1kPa rather than a ridiculous 87kPa. That implies about 1700N of force, which is about a 200ms pressure wave duration.

I don’t know if it’s real or valid, but that’s what the math suggests!

Edit: My wife thinks she’s funny (she’s right)

  • She complained that I hadn’t replaced the drawing of the circle with a little stick figure going “aaaaahhhhh!”
  • Also, today when she was helping me get dressed, she says “Hmm. What should you wear? How about a T-shirt?” And she tosses me this one –>

So, things got interesting this past Tuesday after I threw down my last post about ST and HP and whatnot.

I was doing some yard work in the backyard, removing a large cluster of thorny plants. My intent was to kill them permanently by burning them down at the root. The only fuel on hand I had was gasoline, and since I’d seen gas fires before, I didn’t think much of it.

Well, I coated the pile of plants and the roots with what I thought was a properly sparse amount of gas. Alas, the fuel must have vaporized and concentrated under my deck, so when I went to touch off the fuel, it exploded rather than burning. 

My two children were both outside, but are fine. I got thrown to the air for 6-8 feet and landed in the grass. I did manage to break my heel, but that is seemingly the only ill effect. Well, my butt is a little sore from landing, as is my neck. I landed two yards away (so 8 points of concussion damage, with double knockback, if you’re playing GURPS). I think the damage to my heel was caused by the deck, rather than the landing. I’m not sure. When the explosion occurred, I only realized it when I was able to orient myself – which happened while I was still airborne. 

After the landing, I examined my kids from a distance, and seeing they were fine, examined myself. No gross trauma, no obvious burns, but my left lower leg made horrible popping and settling noises when I moved my (sore) ankle. My wife got my 6yo daughter calmed down, and then saw to my 16month old. My eldest helped me with a two-sided splint. I used a dowel rod, a left-over garden stake, and my leather belt. Long stake underneath the long bone to the arch of the foot for lifting support, and the dowel on top, running along the top of the arch. Wound the belt around both – it kept it nicely immobile. The ER doctor would later express some admiration at my handiwork under pressure. Go me?

Net/net, the X-rays show a broken heel, but the tibia, fibia, ankle bones, and the rest of the foot bones are all fine. No burns, no impaling injuries, no singed eyebrows even, and I didn’t inhale flaming gasoline.

So the only real impact was the heel. Plus vastly accelerating our plans to replace our deck with something new. Demolition started early, I guess. The explosion drew out all my neighbors (some said they saw the fireball) and the concussion knocked a tile off the inside of our fireplace.

Game Related Stats!

  • I had a fuel-air explosive going on.
  • It threw a ST 10-11 person 2 yards through the air
  • Probably counted as a tamped charge
  • I definitely crippled my lower left foot in the blast. That’s 2-3 HP right there.

If it’s 8 points per yard of flight, so to speak, then I needed 16 points of knockback damage. Since I’m not dead, I figure this sort of blast had double knockback, which means about 4 HP of rolled damage.

This reinforces my thought about needing a HT roll to shrug off injury from crushing/concussive damage.

Parting Shot

A few final notes:

  • I got lucky. Really lucky. I could have easily been killed. I get that: Darwin Award Runner up T-Shirt has probably already been ordered by my relieved but sarcastic family
  • Kerosene rather than gas for burning things off. Flash point is a real thing.
  • My wife will not let me near the BBQ for a least two or three seasons. I do not blame her for this.
  • When Katy Perry sings about becoming a firework and shooting across the sky? She definitely did not think that the entire way through. Although technically I was a krowerif.[1]
  • With no small amount of irony, the author of Gaming Ballistic became a ballistic object himself. Go ahead and laugh. I do.

[1] That’s a firework backwards. Because the colors burst, I shot across the sky, and made me go Ow Ow Ow!

What? Not funny? It was funny as hell while I was still on Percoset. Fortunately, the need for that has abated. I’m making do with ibuprophen now, and not much of that either. My splint was replaced with a cast until the swelling goes down. Probably two weeks.

And the Rockets’ red glare, the Bombs bursting in air,
Gave proof through the night that our Flag was still there;
                                   — Francis Scott Key (1814 broadside printing)

Pretty much any time that foes gather together in convenient lumps, someone is going to try and find a way to paste them with whatever the genre equivalent of a cluster bomb strike is. It’s only natural, really – and well supported by some historical studies. Here’s one from the World War II Databook (Table 57, p. 257):

The percentage of battle wounds to british soldiers by weapon 1939-45 overall was:

  • Mortar, grenade, bomb, shell ………..75%
  • Bullet, AT mine………………………10%
  • mine & booby trap……………………10%
  • Blast and crush…………………………2%
  • Chemical………………………………2%
  • other……………………………………1%

While individual battles vary (at El Alamein, I saw a note that 75% of the wounds were bullet wounds), the overall trend seemed to support the conclusion that small arms fire, by and large, held foes in place so that artillery could turn them into casualties.

In some respects, this predisposes the conclusion, because on the one hand, plentiful and easy access to person-killing explosives is a thing of moderately recent history, over the last century or so (though obviously if the bombs are bursting in air, two centuries or more would be accurate as well).

The #1 genre in RPGs, though, is still epic fantasy. And epic fantasy has its own version of artillery, which is the battlefield wizard. Such characters fling pretty potent area effect spells about the landscape, either destroying foes, destroying or shifting the landscape itself, or perhaps both. More on that later.

The key bit for this segment of Violent Resolution is how well and easily do the sample games allow for one attack to impact multiple foes. And that’s what it’s really about, at the highest level – a directed attempt to inflict harm on one or more targets. Well, most of the time, since one of the original effective uses of explosives is to batter down a foe’s fortifications.

Fate Core

The rules for explosions in Fate can be a bit tough to find, but they’re tucked under “multiple targets” in the index, and found on p. 205 of Fate Core. As with everything, the rules are basically the same – you choose your action (Overcome an Obstacle, Create an Advantage, or Attack are the most likely here), specify which, if any, Aspects, Stunts, or Extras are being invoked, and roll.

The rules for area attacks are straightforward if broad (a descriptor which can accurately be applied to the entire system). Area attacks are adjudicated by rolling the dice as normal, and then applying the strength of the attacker’s result by distributing it to all foes that are in the area. If you happen to roll poorly, all the targets in the zone may get off scott free. If you roll very well, then you’ll likely have an intermediate to low effect on your foes, due to the requirement to split successes/margin among your targets.

As a concrete example, if you toss a grenade or sling a fireball at a group of four foes, and you have +3 in the skill and the nature of the weapon (by dint of Weapon Ratings, special defiition of an Aspect, or whatever) gives another +2, then when you attack you’ll tend to cluster around 5 shifts to divide between the four targets (basically 1 stress each, with 2 on one foe of your choice, but you could notionally put all 5 on one foe and ignore the other two). A great roll would give 9 shifts to distribute. The victims defend against the attack shifts allocated to them, not the total.

Naturally, this is modified two pages later, allowing for zone-wide attacks to be a common thing if the situation demands it.

Alternate Takes

With a nod to the Fate Fractal, one can also treat the explosive device itself as a character/aspect with its own attack skill (or weapon value) and stunts. This is the method suggested in a thread on how to handle grenades in the Fate Core Google+ community. The boom-generator is inserted into a zone, and on detonation, attacks everything in the zone, or maybe even the zone itself, with a particular skill.

Depending on the referee’s preferences, one could tag it with a Stunt that attacks with full skill on everyone in the zone individually. With the right balancing appropriate to the genre, this can be tuned to a particular effect. Massive, catastrophic damage to all in the zone (a disintegration grenade!) could be achieved by having the base attack be some ridiculously high value – 6, 8, or even 12 shifts would make short work of anyone not able to invoke the proper aspects for Cover, Armor, or Luck. A low-grade attack with only one or two skill would have a decent chance of not hurting anyone, and at best would tend to apply a few shifts of stress or consequences.

Aggressive Landscaping

The definition of everything as a character with its own aspects, stunts, etc. means that using explosives creatively does not suffer from math overload or endless page flipping. Want to blow down a wall? Decide on the attack strength of the explosive, the defensive strength of the wall, and roll it. Stress and consequences can be assigned as needed. A high-enough consequence might bring the entire building down, while a mild one might allow a free invocation of an aspect when attacking that section again. Stress instead of consequences might be cosmetic damage, such as scorched paint or blown-out windows.

The narrative bent of the game keeps the focus on what the result of the attack, advantage, or overcome action is, not how many LottaJoules of energy were in the grenade.

Arcane Explorations

There is really no difference inherent to a magical explosion as opposed to a mundane one. They’ll be treated the same way in all cases, subject to the usual variations based on Aspect, Stunt, and Extra. From that perspective, it’s handy and self-balancing. Proper choice of aspects will keep magic magical if desired.

A Sufficient Quantity of High Explosives

How does one differentiate between a hand grenade, a Javelin missile, and a small antimatter charge in Fate? Dramatically.

The mechanics support various sizes of explosions largely through the ability to either use Extras to define the strength of the attack, or to treat the exploding plot device as a character by itself.  While caution should be used in assigning these values and care must be taken to keep them balanced for the style of play desired, there’s no reason not to allow scaling up the boom to reflect in-game “reality.”

Night’s Black Agents

Explosives are called out as a great equalizer in the battle against the Vampires, since there’s simply only so much that a physical body can take. Explosives up to and including a suitcase nuke are treated in the game rules.

The mechanics are geared towards personal deployment, and grenades are tossed with a difficulty set by range, such as 2 for Point Blank – which is touching range. And you’re throwing a grenade. Might want to rethink that one. But they can be thrown up to Near range (30-40m). Rifle grenades and other proper toys can reach to Long range (100m). Since the Mk 19 automatic grenade launcher can fire up to about 1,500m, allowing shots at Extended Range with the proper skills and spends isn’t out of the question.

Once you deliver the boom to the target, the explosion is figured as damage dealt based on range from the victim to the source of the blast. There are three considerations – annihilation, damage, and debris. Annihilation is just that – instant death, no saving throw, no passing go, and no collecting $200. If you’re in the damage range, you automatically take a hit, and it’s a significant one – a die of damage plus three times the explosions Class (see below). In the Debris range, you get a die roll (Athletics) to avoid the effects, but if you fail, you take a die of damage plus the explosion’s Class.

A Sufficient Quantity of High Explosives

Explosions in NBA are rated by an explosion Class, a number from 1-6. Class 1 explosions include homemade small explosives like a pipe bomb or door-busting explosive foam. Typical frag grenades are Class 2, and Class 6 is a suitcase nuke. Large explosions are possible, but are in the realm of plot device. You don’t get an annihilation range until you hit Class 3, and even then that’s only Point Blank (the RPG goes off within touching distance).

There’s an interesting bit of specificity for Class 5 explosions, which have a Damage range of Long. The only range farther than that is Extended, which is fairly arbitrary. So the book lists 240m as the debris range here. Probably a needed amplification, though an unusual one given the broad strokes that the game usually paints with.

Cover and armor are treated as an increase in effective range. If you’re behind appropriate cover you’re treated as being one range band farther away. This would need to be adjudicated with some discretion, however. Being inside a battle tank when a hand grenade goes off will probably offer total protection. The odds of being inside such armor given the genre are probably fairly low, but being behind a fortified door, castle wall, or other thick protection is probably well within the normal expectations of the thriller.

Dungeons and Dragons

The salient feature of the Wizard in the CHAINMAIL wargame was the fireball spell, and that seems to have defined spellcasters – or at least “magic users” ever since in many ways. CHAINMAIL was a wargame, to which RPG elements were derived. While spellcasters of all stripes have come a long, long way in the last 40 years of gaming, in D&D they started as a stand-in for artillery, and to some extent, that is still how they are perceived, fairly or no.

While there are many, many ways in which D&D magic users are no longer simply mildly mobile cluster artillery, for the purposes of this article, we’ll treat them within this narrow window – how to lay down the hurt on a whole group of foes at once.

Combat Lullaby

Ironically, the first time this really seems to come into play in many games is not a fireball at all. It’s the Sleep spell, which is such a staple of D&D in my experience it turns into a go-to, must-have spell in nearly all games I’ve played in (that’s a personal observation, of course). This includes the OSR-flavored Swords and Wizardry.

It’s a first-level spell, which means as soon as the caster has access to the proper spell slot (maybe starting the game for many magic-users), she can threaten creatures from 5-40 HP in value, from weakest to strongest, within a 20′ radius of the targeted point. 5d8 HP is enough to, on the average, snooze out five 1 HD creatures in the middle of a fight. Almost uniformly these slumbering foes meet inglorious ends at the sharp end of the PCs weapons after the surviving stronger monsters are dealt with. The spell scales, too, at an extra 2d8 per level of spell slot. So a 7th level spell slot will roll 19d8, even threatening fairly powerful heroes if they’re caught alone – the spell has no saving throw.

It’s not spectacular and there’s no fiery glare, but area effect spells are available right out of the gate.

Crowd Pleaser

The iconic fireball, the only spell available to the CHAINMAIL wizard at first, it too impacts a 20′ radius sphere. At its weakest (a 3rd level spell slot) it does 8d6 damage (half damage if you throw yourself out of the blast with a Dexterity save) to all creatures within that sphere, and the sphere wraps around corners, meaning cover is no protection from this magical fire. If a very high level character throws one with a 9th level spell slot, it will do 14d6 damage.

Relatively speaking, a few fireballs will play havoc with a tightly packed formation – which like their fragmentation grenade or artillery inspiration, is the entire point. Given a 1st-level character in D&D5 will have on the order of 6-14 HP, even the entry-level version can pretty much vaporize a small cluster of such fodder. Against a more potent foe, it will still be a threat. A 5HD monster might have 25-40 HP, and the damage done by the spell is 8=48 HP, which can nearly incapacitate the middling level 5HD creature even if they successfully save.

Explosive or area effect spells in D&D can get darn nasty, such as the potent Meteor Swarm – what may well be the baddest thing to hit the dungeon since TILTOWAIT. A 9th level evocation spell, it strikes everything in a 40′ sphere with 20d6 fire damage and 20d6 bludgeoning damage. It’s going to take a very, very high level fighter to not get turned into paste by that one.

That being said, a 20th level fighter (1d10 HP per level, average 6 HP) with CON 18 (+4 HP per level) has a pretty good shot at tipping the scales at 200 HP, so 40d6 total will be a mighty blow at 70 or 140 HP average, but not necessarily an automatic fight-ender. Against a high-level spellcaster, with but 1d6 HP and CON 14 or CON 16 will eke out 6-7 per level, for 120-140 HP, which is a serious threat of one-shot incapacitation. This is a deservedly powerful spell.

Magical Claymore

D&D also features directional area effect spells, such as the Cone of Cold. Doing 8d8 out of the gate and 12d8 at max power, this spell reaches out 60′ and freezes things in its path, with a width of effect equal to it’s length (it’s an equilateral triangle). This makes it intermediate in effect extent and requires some stand-off . . . and no friendly characters blocking your attack line.

Savage Worlds

This is a tactical game meant to be played with miniatures and a map. As such, the rules for using explosive and area effect attacks are built around a blast template – a usually-circular cutout that shows the size of the affected area. To toss a grenade or cast a spell into an area, one makes a skill test using the appropriate ability (Shooting, Throwing, or an appropriate spell skill all come to mind) given the range being targeted. Success means you land the template where you want it to be. Failure means it deviates randomly, and with the right flavor of flub, you can indeed be caught in your own explosion, though the rules do prevent the thing landing behind you.

Damage is by weapon or spell, and affects everyone within the blast zone at full value. There is no effect if you’re out of the zone, and as always, impacted characters are up, down, or off the table. The two grenades listed in the Deluxe rulebook do about 3d6 damage to all targets in the blast radius, which means getting caught in the blast zone is as bad as getting hit by a .50 BMG (2d10) or 14.5mm machinegun (also 3d6). That is to say: very, very nasty.

Claymore of Doom

The actual claymore antipersonnel mine makes an appearance in the rules as well, and uses the formulation for canister shot. Basically, the mine reaches out for 24″ (about 50 yds) as if the blast template slides along its entire length, impacting everything it touches for 3d6 damage. Effectively, this turns both canister and the claymore mine into a cylindrical area of effect weapon. The damage here is about right given what a claymore actually is. The shape of the effect is a bit odd – a cone effect might be a better fit.


As one would expect based on its treatment of firearms, GURPS has a fairly detailed treatment of explosions and area effect weapons. It also allows for a bit of variation in blast effects.

Collateral Damage

GURPS assumes that explosions have a point of origin (this isn’t unique) and that the damage is strongest at the center for a “normal” explosion. Every explosion has a damage value and that only applies to the actual target struck. For everyone else, damage is rolled normally, but divided by 3x the distance in yards from the target. That means if you’re hit directly by a 6d explosion (enough to take Joe Average from fully healthy to his first death check at -HP on an average roll) you’re liable for the entire 6d, but at only 2 yards distance, you’re rolling 6d/6 (about 1d), and by the time you hit 12 yards, you’re looking at 1 point of damage at the best case, ever.

Unsurprisingly, the rules note this: the maximum impact of an explosion goes out to twice the dice of damage, in yards. That’s another way of noting the same point – X dice of damage will have a maximum roll, ever, of 6X, and damage falls off as 3D (three times the distance in yards). So for only one point of damage, you’re looking at 6X/3D = 1, or D = 2X. The math is not shown, merely stated – “an explosion inflicts ‘collateral damage’ on everything within (2 x dice of damage) yards. But you can see where it came from easily.
The blast or concussion damage, then, isn’t a big deal unless the explosion is very large or you’re very close to it. The baddest hand grenade in GURPS High-Tech (the M67) does 9d damage, which means from the blast itself you’re safe outside of 18 yards – which of course means in reality it’s impacting a sphere 36 yards in diameter, which is rather larger than the blast zone of the Meteor Swarm spell, but the zone in which you’re even liable for about 1d damage is only two yards in diameter.

That being said, the game gives you the ability to calculate the blast effects of the CBU-55/B as well, a 500-lb fuel-air explosive bomb which detonates for 6dx65 damage – 390 dice, which means you need to be 780 yards away – over 0.4 miles – before you’re truly safe. And yes, this can scale up to nuclear weapons if desired: the “Little Boy” bomb released over Hiroshima, Japan on August 6, 1945, hit with roughly the force of 12,500 tons of TNT