We have explained this before but it seems some of you still can't get your head around what exactly SpyParty is. Do the words "asymmetrical two player stealth duel" not make it immediately apparent?
So: SpyParty is a game by Chris Hecker, a programming guru who was responsible for a lot of the exciting procedural animation wizardry in Spore (and none of the disappointing missing gameplay elements).
Each match has two players - a spy, and a sniper. The spy's job is to complete a mission while blending in with an AI crowd. The sniper's job is to assassinate the spy. I really don't understand why people find this so hard to understand, but there you have it: they do. The video below breaks this down into words of mostly one syllable to make it even more comprehensible.
SpyParty might just make it as an eSport; it made an appearance at Evo 2013. If you're interested in the concept, don't let the admittedly wince-worthy graphics put you off; buy in to the $15 beta now before the promised graphical overhaul.