I dunno if anyone has really played this here, but Madness Interactive is an amazing 2d twitch shooter based on the Madness Flash movies. The game is amazingly addictive and nothing is more satisfying than unecessarily unloading an entire clip from an AK into someone's face after they got a shot off on you. Maybe not realistic gore but still very violent nonetheless. Anyway, I wholeheartedly recommend this game to anyone, you can d/l from
www.flecko.net.
Oh and its open source so theres lots of Mods.