okay but what if a nerf style foam dart FPS game where all the bullets are universal ammo, but they're ALL persistant and physics objects.
They makea squeaky noise when they hit things. You have a shoot button, a reload button, a RESTOCK button, and a grab button.
Grab picks up darts from under you, reload loads the next magazine into your dart-gun, regardless of filled status.
HOWEVER, you have to fill each emptied magazine manually. Find a place to hide, hold "RESTOCK" to fill empty mags.
you just hold that button down until each empty mag (or half filled one) is completely filled, but while doing this you are vulnerable because you can't hold the gun too and be ready for combat, thus there's a short wind down and wind up animation for Restocking. Reload is a simple FPS style reload, doesn't take long at all.
Fire rate, force, ammo capacity, that's dependent on each gun, but the darts are the same, and each player has a set number of mags that each start full.
So it's sort of a cross between a colourful, non-violent multiplayer and/or SP campaign based FPS, and a hide-and-seek game when you need to restock, plus trying to catch clusters of foam darts to restock when you get a chance, as they scatter away from you when you run over the piles.
You can shoot while grabbing but you really need to crouch to get darts off the ground, and your aim will potentially be off because you're grabbing darts too, worse for two handed guns.
I think there could be good mileage in this sort of design of an FPS game. Bright, colourful environments rather than grungy realistic ones, for the most part, but some nice grungy abandoned warehouse/urban exploration style environments with colourful graffiti to mark out areas and stuff if you want a darker environment?
Levels built around hiding spots, not for sniping, but for safer restocking, stealth mechanics so crouching can deaden your foot sounds, mobility options maybe?
