Wednesday, October 21, 2009

Bringing in Gamma World

Given the harsh nature and post-apocalyptic atmosphere of Tarraxian, I've started bringing in things from my Gamma World 2nd edition boxed set, purchased on Ebay earlier this year. While the concepts fit just fine, I find I'm having a bit of a problem with the conversion. I have followed the guidelines in the 1st edition DMG, but I find them somewhat lacking. Mainly, my problem with GW to AD&D game mechanics is the scale of hit points. A Gamma World character starts with 1d6 hit points for every point of Constitution they have. Assuming each hit die yields a mean of 3.5 hit points per die, that means that a Gamma World character with Con in the average spread (9-12) has around 31-42 hit points their first foray into the world. By contrast, D&D characters start with 1 (2 for rangers) and generally seem to have 3-6 hit points... (my characters have a bit higher since I start at 1st level characters at full hit points)
The monsters and (arguably) the weapons and hazards of GW are scaled for such characters. Badders, who have six hit dice and look to be the "starter" monsters for a beginning group of GW characters (who will have, on average, between 9 and 12 hit dice) are actually more like monsters for AD&D characters levels 4-6. Likewise, low intensity radiation that would hinder a Gamma World character will outright kill many of my AD&D characters.
Since I am in fact playing AD&D and not Gamma World, I want to keep things AD&D-centric in terms of damage and scale. After all, who knows when the party will decide to seek the way back to their own home world, right?

Edit: Tonight I pretty much ran the numbers as they were. This resulted in the druid gaining an unfortunate mutation (no pain sensation) and in the party being defeated by a security robot... luckily the bot was using knockout grenades and a paralysis rod. The characters actually had a brilliant plan involving an unseen servant and several live grenades, but unfortunately they didn't know their grenades were just knockout gas, to which the bot was obviously impervious. We'll pick up next time... who knows where our heroes will wake up?


  1. As it stands, Gamma World creatures are HD equal to Con.

    If you want to keep it in scale with AD&D, then you can do a few things:

    1). Give mutations to existing AD&D creatures which keeps the HD/HP in scale.

    2). Ignore the Con = HD and give GW creatures HD based on AD&Disms.

    3). Instead of rolling Con d6, use Con score as HP.


  2. I am not sure what edition they first appear in but the Menarl (10 armed snake) is pretty much my favorite monster of all time.

  3. Timeshadows covered it pretty well. A small addition

    4) GW starting characters are equivalent to AD&D characters levels 4-6. There are no low-level threats in GW, it's just that darn deadly.

    For me, the flavour fluff is the important part of a conversion. Stats/mechanics only exist as a short hand notation of how tough/bad ass something is. I always use method 2. Things are cool not because of what they can do, but because of how DM describes and uses them.

    Security Robot: Find a D&D monster that is roughly the challenge you are after and use its stats say 4th lvl fighter in platemail. Maybe add twist or two such as DR5/Bludgeoning and a "Taser Baton" which is really Hold Person spell.

  4. I forgot...

    Driving home the flavour / "Things are cool because of how DM describes and uses them."

    With that security robot, describe how shiny it is, how it jerkily it moves, get up and do some robomovement pantomime and talk in cheezy robo voice "Bzrrt, quit resisting." "Exterminate!", the klang of metal from weapon impacts. strange coloured wires, bright sparks, the smell smoke and melting plastic when it takes some serious damage. Sterile, cold, analytical. make it different than the typical brutish, bloody struggle with barbarous humanoids.

    That's how I'd work it at least.

  5. Thanks for the input, all.

    I recall now that I did fudge a few things downwards to push the scale more in line with AD&D scale, but most of that was Radiation Intensity, and mainly becuase I didn't do my homework enough to get a feel for how the mechanics worked. Of course, Gygax suggests in the DMG that radiation should hose AD&D characters and magic should hose Gamma World characters...

    Anyway, I'm going to play it by ear for now. I'll try to run it as close to GW as possible, but some numbers may need a bit of adjusting. I might also take some monster stat blocks from AD&D1 and, as TS suggested, dress them up as familiar GW creatures like Arks and Badders.

    (Well, familiar to me; I don't think any of my players have ever played GW before.)

  6. Speaking as one of the unconcious ones, last night was a blast. The best moment of the night was when the grenades went hiss instead of boom. We knew we were dommed, but threw in our all. The thrill of victory and the agony of defeat!

  7. Scale can be difficult in cross-genre games. The route I've generally used is straight up conversion to the new system.

    Wha-wha-what?! Blasphemy, you say! But that was how I interpreted the conversion rules in my old TSR books and I used that as a guideline.

    FOR EXAMPLE: when my players' AD&D characters suddenly ended up in Boot Hill, six-shooters didn't suddenly start doing D6s of damage to hit points...they took damage straight off a character's Strength attribute, just as with a Boot Hill character. Now if a shotgun (or a cowboy for that matter) had been brought back to "AD&D world" it would have been a different story (different universal laws, ya' know?). It worked the same in Marvel Super Heroes (lot o characters only getting "Typical" to "Excellent" strength unless they had girdles of giant strength, for example)...until the characters returned to their own game world, they operated under the auspices of the new universe.

    So for GW I'd have the characters convert their "standard" hit points to "GW hit points"...I'd consider 'em all to be Pure Strain Humans (yes, even the dwarves and mutations, right?) and give 'em D8s times their Constitution. If this resulted in less than their AD&D hit points, raise 'em to the higher level (to represent their luck, experience, etc.).

    You can probably allow them to use their standard hit tables (if you're feeling generous) but I'd probably still use the weapon matrixes o GW for modern weapons. And radiation and poison tends to be deadly for both GW characters AND AD&D characters...keep the levels low to non-existent if you're worried about your players' feelings.

    Good luck!