Use the following:
- Swords & Wizardry Whitebox for the base rules (primarily for combat)
- Instead of using classes, just assume everyone is a mutant; have players roll up stats and then roll up 4 random mutations for their characters
- Gamma World had levels, but they were pretty meaningless; perhaps do away with levels and just give all characters Constitution + (some other stat – maybe Wisdom) hit points; all combat bonuses are based strictly on the character’s stat modifiers; for saving throws, roll 1d20 (+ applicable modifiers) equal to or greater than 10
- Use the Metamorphica to determine mutations (at 650 mutations there’s a lot of mutational goodness in that supplement)
- A source to determine random junk, either the Junkulator or my Ultimate Grand Unified Junk Table (analog edition); assume that new characters start with 10 pieces of randomly generated junk
The nice thing about using Swords & Wizardry Whitebox is that A) it’s rules light and simple to play and B) everything does 1d6 damage, so you don’t have to spend a lot of prep time trying to decide how much damage a mutant claw does vs. mutant acid spit vs. mutant quills. It’s simple: they all do 1d6 damage.
So, the kicker in all this is a system to sort of jury rig all that junk loot the PCs find into more effective items, particularly more effective weapons and armor. I call the system Junk Rigging, for lack of a more clever or imaginative name.
The heart of junk rigging is Item Complexity. A rigged item’s complexity is equal to the number of different pieces of junk that were combined to make that item. To help keep things somewhat managable, the maximum item complexity a character can use is 3, plus their Intelligence modifier (either +1, 0 or -1), for a range of 2 to 4. Maybe some mutations or other special abilities can be incorporated to increase maximum complexity at a later time.
It’s important to remember that junk rigging isn’t real science or real engineering. It’s gonzo-post-apocalypse engineering and the idea is for players to come up with wacky stuff made out of everyday junk they find in the atomic ruins. The only rules, aside from the following guidelines, is that whatever item a player junk rigs together should be comprised of bits of junk that plausibly somewhat relate to the item being made. For example, if you want to make a junk rigged melee weapon, you should use stuff that’s hard and/or sharp. Making a club out of styrofoam cups isn’t going to do any damage.
However, nothing stops players from trying to make more gonzo stuff, like converting a laser pointer to emit a lethal beam by hooking it up to a car battery and adding some circuits and stuff to it. It just has to be somewhat plausible.
Junk Rigged Weapons
Once again, this is where S&W Whitebox comes in handy. Every junk-rigged weapon does a base of 1d6 damage. However, weapons also have a bonus, called Weapon Class, equal to the weapon’s complexity minus 1 (C-1). Weapon Class is added to both attack rolls and damage rolls (kind of like a magical enhancement bonus for a +1 weapon, for example).
The downside is, the more junk you cobble together to make a weapon, the more fragile and likely it is to fail when you use it. If the d20 attack roll is equal to, or less than, the weapon’s complexity, it breaks and has to be repaired or remade.
The maximum range for a junk rigged weapon is 60 feet.
Because armor can be worn in lots of little pieces all over the body it isn’t subject to the complexity rules. Each piece of junk loot, either individually or combined with other junk, grants a +1 bonus to Armor Class (AC). However, the more crap you strap to your body, the more you slow down, as follows:
- No armor = 120 feet/round
- Up to +2 AC (equivalent to leather) = 90 feet/round
- Up to +4 AC (equivalent to chainmail) = 60 feet/round
- Up to +6 AC (equivalent to plate) = 30 feet/round
Characters can also employ hand-shields (such as the post-apoc staple, a STOP sign converted to a shield) for an additional +1 bonus to AC. Alternatively, you might use the shields will be splintered rule, where shields can absorb a hit but then are destroyed, instead of granting an AC bonus.
If you use critical hit rules, you might also say that any critical hit scored on a PC breaks a piece of junk armor, reducing the character’s AC by 1.
Assume that any piece of junk that could concievably be used as a bandage or medicine heals 1d6 + Complexity damage. Rendering first aid takes one combat round.
Players might want to combine various chemical substances they loot to replicate the effects of magic from S&W (for example, making a sleep gas). Again, remember this isn’t real chemistry, so it doesn’t really matter what chemical substances they combine. What matters is the intended effect.
So, to successfully combine the chemicals, roll 1d6 equal to or less than the substance’s complexity (in other words, throwing in more chemicals increases the odds of getting the desired effect). If a 6 is rolled, something goes horribly wrong with disasterous results for the PC. It may be fun to use some kind of potion miscibility table to determine the results of a mishap.
Note that chemical compounds will probably need a container, as well. Dangerous compounds allow a saving throw to negate or mitigate the effects.
This category covers a lot of territory, so GMs will probably have to improvise a bit. If players make something simple, like a hammer or a shovel, just assume they now have the appropriate tool. If they want something more complex, like a lock-picking device, assume that higher complexity increases the probably of success (maybe roll 1d6 equal to or less than complexity to succeed with the tool, or roll 1d20 + Complexity over some DC?). The flip side, however, is that the more complex the item, the more fragile it is and more likely to break when used.
Naturally, the GM has final say over any junk rigging combination. Just keep in mind it isn’t real science. If a combination would be feasible in a pulpy-gonzo-comic book-post-apocalyptic way, let the players roll with it. However, if they try to combine a stuffed animal with a coffee mug and call it a death laser, feel free to shoot it down.
You can also still have relics of the Ancients, vastly superior to any junk-rigged item. Just give the spells and magic items from S&W a science-fictiony skin. For example, fly can be reskinned as a jetpack or a gravity harness. Fireball can be reskinned as a photon grenade. Lightning Bolt can be reskinned as a plasma rifle. Just make sure all these relics have a limited number of charges or uses; keep the PCs hungry. 🙂