Keybind system will come eventually - but it is not a priority as the key purpose of this stage is to build up the main gameplay loop, not fuck around with adding settings etc.
Melee already exists - it's a momentum-based system wherein the damage you deal to an enemy is based on how fast you're going when you collide with them.
I don't believe a sniper would be appropriate for this game - this game is about going fast, and I think a sniper would encourage people to slow down and eliminate enemies from a distance which is not in the spirit of the game.
Really appreciate the suggestions!