Project Gungame includes most commonly met features of the io games: plenty of players, level ups, weapons to unlock, map editing and many other stuff for everyone who wants to fight for the top of the leader board.
How to Play
There're several tasks in Gungame: win the battles to earn the money, unlock new weapons and finally create your team.
In the battles you receive money for every killed player and also get some XP. Depending on the map type the game options may change: capture the flag, building allowed / disallowed, PVP or team mode. The creator of the map can enable / disable these options during the game. The rules're available before you've joined the map.
If you want to create or join a team, you'll have to sign up.
Also in Project Gungame pay attention to weapon reloading. It's not automatic, but with R key. You can switch the weapon by Q and continue game with a secondary weapon. Watch the charge level of jetpack, otherwise you a chance to crash, fall and die. That would be shaming.