We've currently developing a similar game called SquabPie http://squabpie.com/ It's still in early alpha, but already playable (one small server) and quite stable. We have WASD controls, skill shots, no predefined classes with customizable weapons instead; deathmatch and "team vs team" modes. Visuals are not very stunning :) because there are only two (and a half) developers, but we're working on it. We don't have much players yet, but there is always one or two devs hanging out in chat, so we can keep you company.