OpenLieroX
This is a fairly new game, only about 500 players in total BUT IT KICKS ASS.
Your basically this little guy,its sort of like worms but not turn based, and you can always pick 5 guns to battle with.
You can go against npcs or play online, and THE WEAPONS ARE FUCKING CRAZY!
There are over 100+ mods ( sets of guns ) that come with like 20-80 guns in each one, and there is fucking guns like ones where you summon pacman to eat the shit out of your opponents, or even a giant nuke beacon that will FLOOD A WHOLE ROOM FULL OF EXPLOSIVE SHIT, thats right, EXPLOSIVE SHIT.
Anyways, DOWNLOAD THIS SHIT UP, ITS A 2D SCROLLER AND WILL FUCKING BLOW YOUR DICK OFF.
Forgot to mention.
YOU CAN FUCKING EAT THROUGH SOME THINGS, THATS RIGHT YOU ASSHOLES, EAT THROUGH SHIT!
For example, there is a level that is COMPLETELY underground and its ALL DIRT and the only way to move is to eat through that shit, literally.
Also, YOU CAN FUCKING USE A NINJA ROPE.
http://sourceforge.net/projects/openlierox/
SERIOUSLY, FUCKING DOWNLOAD THIS SHIT RIGHT NOW.