So the sling would be a projectile/throwing weapon, and if your hands are full when you pick it up, it's goes into your inventory as a container to hold 'ammo'. Anything you throw with it (assuming it doesn't break like an egg would) can be picked back up and thrown again, but enemies could also pick it up
It would be for, obviously eggs and snowballs since those are already throwables, but for other stuff it could use rocks, spiked balls, possibly potions, or just any 1 pixel item
Throwing eggs I think would be about as funtional as it is now, but if you let an egg rot and throw it at a living/humanoid enemy it has a chance to make them puke and end any potion effects they've got on. I think eggs would have to stop auto-reloading in your hands if a sling was added so there would actually be a purpose for this part
Rocks could drop from orcs in the stony field and would just be plain damage. Spiked balls would have to be a rare drop I think, since once you get one you can use it infinitely as long as it doesn't get lost/stolen, and you'd be able to see it with metal detect so losing it wouldn't be a huge issue
Potions could have a 50/50 chance to shatter and deal damage and maybe cause bleeding, or give the person/creature a weakened effect of the potion (speed but it doesn't last as long as if you drank it, stone skin but with less defense and slightly faster movement). I dunno how this would work with hitting friendly players, since it could potentially help them or kill them
Other single pixel items could have unique effects.
Brains/hearts could cause human enemies to puke (but not orcs since they probably wouldn't care).
Snake fang would cause poison.
Gems (including sun/moon stones and blue bee shells) could charm an enemy for a certain amount of time, maybe based on their value.
Rat teeth could have a very small chance to give disease.
Frags and hooves would be damage
Charms could have effects based on the individual charm, or just work like gems
Bat fang could have a chance to do a drain attack, and whoever picks up the fang gets the health from it
