would be interesting, but sadly could not be large scale AND appeal to a audience large enough to keep the game alive.
or for example the case of agar.io, the most in depth you can go with something like that.
ontop of that if you do try to make it large scale, there is the problem of accidentally exposing the wrong group of people to such a niche community.
you COULD however make it feel multiplayer by making everyone else randomly generated bots.
but now that aside: mechanics time
- hitboxes obviously should increase with weight. as then there is a factor of trying to avoid fights to stay skinny with a small hitbox, or killing as much as possible for the biggest damage/health increase
- most weapons should not be dead-on accurate, to help enforce the above rule
- the kill barrier should not move faster than the slowest person, should instead move at 90% of their movement speed.
- if 3D, map verticality and the restricted movement of people at higher weights should be considered. dont want to discourage killing in a weight gain game.
- possibly some sort of incentive for targeting people at a higher weight than you? such as some sort of weight multiplier when you kill someone bigger than you.