Phoenix Network Forums

http://www.soldat.pl/main.php

example screenshot: http://static.soldat.pl/screens/promo/Image1.jpg

" Soldat is a unique side-view multiplayer action game. It takes the best from games like Liero, Worms, Quake and Counter-Strike and gives you fast action gameplay with tons of blood and flesh. Soldiers fight against each other on 2D battle arenas using a deadly military arsenal. This is what multiplayer was invented for."

basically it's a sidescrolling, net-play shooter. you move left/right/jump/crouch with keyboard and move crosshair with mouse. left click shoot, right click jetpack. grenades and such also.
pretty fun.