Q3 railgun @ 2000 DPI 4 life.
I should probably freshen up my twitch too, feels like forever since I played anything competitive.
I still don't think
Mount & Blade has any multiplayer support, but Claus from Aventurine/DFO pointed out that combat shared some similarity. (Movement, manual blocking, melee) The AI was fucking horrid way back when I played it though. Demo is a small, free download. It's ugly, but fun. Weapons were quite diverse. Mounted combat included.
If you see yourself playing mainly ranged I guess any fastpaced FPS will do. If you're into alot of melee, best bet would be to find something that involves alot of movement, strafing, fast turns etc. judging by videos.
I'm still crossing my fingers for an Alfar railgun.