for the above rpg thing, i've been thinking of repurposing it into a postapocalyptic/space western modern-tech battle game in the vein of fallout
tell me what you think of this mechanic
on-foot characters (who are by-and-large the foes you will be fighting) are split into three categories, fire emblem style: shotgun, rifle, and automatic. they interact in a simple rock paper scissors fashion where shotgun beats automatic (because shotgun can do more damage faster at automatic ranges, often critting), automatic beats rifle (automatic fire puts pressure on rifles, making it hard to line up their single hard-hitting shots) and rifle beats shotgun (because shotguns are too short-ranged to hassle rifles well, meaning that rifles outdamage then and often crit on them)
the fourth on-foot weapon, explosives, are rare and hard to come by but function as a catch-all 'forget you' to any enemies that your player cannot be effective against. when finally posed with enemies who are either mechanical or straight vehicles, the weapon triangle stops doing direct damage and instead begins to do debuffs, with explosives (now having become common enough that they can be used every fight) become the damage dealers and finishing moves
for reference, versus vehicles, automatics slow the target, rifles break armor and shotguns lower accuracy and increase crit chance. feasibly, in lieu of rockets, leveling enough shotguns on a single vehicle and then hitting it with a high-critical rifle will kill the vehicle, but it is likely that (without hassling it with automatics) that it will kill you before you can crit it to death
it is typically faster to kill them with explosives unless you have a party member who crits out the ass or something