A suggestion:
A twenty-something signs up to test high-tech weapons in a series of Duels to wipe his debt. His next opponent proves to be his equal... but if one of them doesn't win soon, both will lose!
Just my preference, but this one combines the mention of duelling to test weapons (which is an awesome freaking idea) along with the idea that one has to kill the other, or neither will remain alive.
I think the "weapons testing by way of duel" is the clincher, the unique twist on action concepts that immediately sets it apart (kind of like the idea of curving bullets in Wanted, for example). And the "both will lose" part makes sure they know that it has a sort of Battle Royale-style requirement for death, which would immediately get someone interested in the possible tension it might allow, since these two are apparently equals in skill.