I've been a fan of the shoot 'em up rpg Quake since the first game was released back in 1996 - I played a first-level-only demo that shipped with a computer mag and just had to get the full game. (Quake One still has a strong following here...)
Now id software, the developers of Quake, have released a free-to-play online version called Quake Live and it's awesome! Check out the unofficial trailer below and then go register at www.quakelive.com