Thank you! I recommend Ben Milton's Knave for this (as Wastoid is based on its rules). Beyond that, I can share with you what I've got from the relevant portion of the manuscript in progress, with two caveats:
- I still have to playtest this (especially the part about calculating HP).
- I'm more concerned with adapting stuff on the fly than careful conversion procedures.
That said, here's what I've got so far…
Ability in Wastoid could refer to the 7 abilities players’ characters have, but most denizens of the wastes are simply represented by a generic “ability” that covers anything vaguely related to what they seem they should be good at. If adapting creatures with hit dice (HD), you can use this as ability. If unsure, give a default ability of +5. [When doing anything else, they have a +0 modifier.]
HP in other games generally runs much higher than in Wastoid. For quick and dirty conversion, add the creature’s HD value to 5.
AP can be converted by looking for a game’s equivalent of light, medium, and heavy armor (often leather, chain, and plate in fantasy games). Wastoid uses leather (4 AP), scrap (8 AP), and combat armor (12 AP), +1 to 2 for a shield, and another +1 to 2 for a helmet. If unsure, give a clearly thick-skinned creature 6 AP and call it a day.
Damage can usually be simplified as d6 for most attacks, d8 for those with two-handed weapons, and d10, d12, or multiple d6 for only the most powerful attacks (like with explosives and high-tech).
Special effects like “double damage from fire” or “two attacks per action” can generally be used as-written in Wastoid. The GM should just take care to telegraph to players when something looks really, really dangerous. Remember, running away is (almost) always an option!