Battlemech Conversions

   Since it looks like the Battletech Universe may be a repeated stop, there are some general rules for converting Battletech Mechs to d20 statistics:

   Hit Points: A basic human being in Battletech (Mechwarrior, at least in the edition I happen to be looking at right now) can take 10-40 human-scale hits – about the damage done by a SRM on the average, equating to 2 mech-scale hits. Basic human beings in d20 have 1-4 hit points. We have a rough match: d20 hit points equate to mech hits. To refine things a bit, note that Mechs are usually complete wrecks long before they run entirely out of armor and internal structure, while d20 units operate unhindered until 0 HP. Just as importantly, d20 uses 6-second rounds – versus Battletech 12-second rounds. Ergo, we’ll need to half the mechs total HP and the net damage from its weapons.

   Fortunately, d20 has “hardness” to help make up for lower hit points. While basic hardness only reduces the damage from physical attacks, due to the advanced armor materials used in modern military units, their hardness also reduces the damage from energy weapons. Most military units are built of advanced steel, ceramic, and composite alloys – giving them a base Hardness of 10.

   Converting Weaponsis a little harder: d20 weapons do variable amounts of damage, rather than fixed amounts – and we want them to do the right amount on average. So the average we’ll want is (Mech Weapon Damage/2)+10. Things are a bit more complicated with the missiles, wherein there’s an average on both sides: only about 70% hit on the average in Battletech, Ergo:

.

Battletech

1-2

3-4

5-8

9-10

11-12

13-14

15-16

17-18

19-20

d20

3d6

3d6+1

4d6

4d6+1

4d6+2

5d6

5d6+1

5d6+2

6d6

d20 Mod

+4

+3

+2

+1

-1

-2

-2

-2

Ammo

             

1

1-2

  • LRM and SRM missile systems should have their base damage multiplied by .7 before conversion, thus – say – an LRM 10 with an average damage of 7 in Battletech and 13.5 in d20 comes out to 4d6. Ultra Autocannons do about 1.5x the listed damage, so apply that modifier before converting.
  • The “d20 Mod” is the to-hit modifier. The heavier weapons are simply harder to aim.
  • Ammo is pretty simple: on a natural attack roll within that range, the weapon is out of action – jammed, needing to be reloaded, damaged, or whatever. While a lot of the missile launchers should have ammo limitations, in practice they rarely run out anyway.

   Movement: Mechs, being tireless and machines, do move considerably faster than humans over the long run: over the short run humans are a lot more agile. Still, simple conversions tell us that 1″ of Mech movement equates to 30 feet per round of d20 movement. Mechs should only “run” at 3x their base movement rather than 4x, but this rarely matters.

   Now, Mechs are generally Gargantuan, which translates to Str +24 (over a base of Tonnage/5. Sadly, as mechanisms, Mechs do not get strength-based DR), use the Operators Dex at -8, take a -4 penalty on attacks against human-sized targets (who get a +4 on attacks against them), suffer from a -12 to Stealth checks and to any attempts at fine work, and have a base AC of 19. Given that they are made of metal – even if Battletech has no real equivalent to Armor Class – and that I have a fondness for round numbers, we’ll call them AC 20. Battletech does include a modifier for movement speed, so we’ll throw in something for that: add (Mech Walking Movement-3) to the base AC.

   There are a few other things: Mechs suffer a -2 “To Hit” (on 2d6) if their sensor systems are damaged, which translates to about a -4 in d20. They can cause more damage by firing more than one weapon at a time – but generally suffer from heat restrictions, a mixture of range profiles, ammo shortages, and facing limitations that restrict this. Few of these problems translate easily to d20, so we’ll be a bit more abstract about it and give mechs with lots of weapons Hammer with a few Bonus Uses (per minute) and count the targeting system as a BAB bonus. Mechs with no heat limitations may be able to use it – and thus maximize their damage – almost every round, but those with more problems may be far more limited.

   Ergo: +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), Hammer with +4 Bonus Uses, and Scrambled Radio Communications. Individual units may have some additional equipment, but that pretty much covers the basics. Some sensory equipment would seem to be in order, but – oddly enough – most of the Battletech rules don’t seem to imply that they have any. Finally, Battlemechs may be fitted with one-shot re-entry systems, that’s purely external equipment.

So, here are a few Mechs:

  • Stinger, 20-Ton Gargantuan Light Mech, 40 HP, Str 28 (+9), uses (Operators Dex-8), DR 10, AC 23, Move 180 (Jump-180), Medium Laser (+2 To Hit, 4d6 Damage), 2x Machine Guns (+4 To Hit, 3d6 Damage), +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), and Scrambled Radio Communications.
  • Jackal, 30-Ton Gargantuan Light Mech, 73 HP, Str 30, (Operators Dex-8), DR 10, AC 24, Move 210, Particle Cannon (+1 To Hit, 4d6+1 Damage), Streak SRM-2 (+3 To Hit, 3d6+1 Damage), Antimissile System (DC 20 Reflex Save to block a Missile Attack 1/Round, counts as an Attack of Opportunity), +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), and Scrambled Radio Communications.
  • Hatchetman, 45-Ton Gargantuan Medium Mech, 90 HP, Str 33 (+11), (Operators Dex-8), DR 10, AC 21, Move 120 (Jump 120), Autocannon-10 (+1 To Hit, 4d6+1 Damage), 2x Medium Lasers (+2 To Hit, 4d6 Damage), Hatchet (1d8+Str Mod), +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), and Scrambled Radio Communications.
  • Quickdraw, 60-Ton Gargantuan Heavy Mech, 113 HP, Str 36 (+13), (Operators Dex-8), DR 10, AC 22, Move 150 (Jump 150), LRM-10, SRM-4, and Assorted Medium Lasers (All +2 To Hit, 4d6 Damage), Hammer with +6 Bonus Uses (7 uses per 10 rounds), +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), and Scrambled Radio Communications.
  • Madcat II, 90-Ton Gargantuan Assault Mech. 194 HP, Str 42 (+16), uses (Operators Dex-8), DR 10, AC 21, Move 120 (Jump-90), Gauss Rifles (-1 To Hit, 5d6 Damage), ER Medium Lasers (+2 To Hit, 4d6 Damage). Hammer with +6 Bonus Uses (Usable 7 times every 10 rounds), +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), and Scrambled Radio Communications.
  • Atlas, 100-Ton Gargantuan Assault Mech. 228 HP, Str 44 (+17), uses (Operators Dex-8), DR 10, AC 20, Move 90, Autocannon-20 (-2 To Hit, 6d6 damage, out of ammo on a 1-2), LRM-20 (-1 To Hit, 5d6 damage), and Medium Lasers/SRM Launcher (+2 to Hit, 4d6 damage). Hammer with +2 Bonus Uses (usable 3 times every 10 rounds). +4 to the pilots BAB, Major Immunity to Atmospheric Conditions (Toxins, Vacuum, Etc), Hammer with +4 Bonus Uses, and Scrambled Radio Communications.

.

   Why these mechs in particular? Well, they’re a fair sampling, the Stinger is one of the most common Mechs in the inner sphere, and they’re a fairly good illustration of why Mechs are considered hopelessly obsolete in the Core Worlds of the Federation-Apocalypse campaign.

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One Response

  1. […] d20 characters are not soft, squishy, mortals to begin with. As covered over HERE, one d20 hit point is roughly equal to a Battlemech (or Megadamage) Hit Point – and the same […]

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