Just played STRAFTAT, a game available for free on Steam (a optional DLC available, I probably won't buy it).
Its pretty fun, games are in always 1v1 and the maps are chosen random, are very small and usually feature some sort of gimmick - so you'll have to orientate yourself fast to have a chance. The weaponset is seems to be inspired by Golden Eye for the N64.
Nothing groundbreaking, but if you like arena shooters, checking it out is worth it - who knows how long it will stay active ;). If you want to challenge me, just write me ;)