[aplummer]

Try Starcraft 2. Games are under 20 minutes and you need to fully commit aggressively to win a lot. Constant attack / harassment / probing or risky expansions(or both).

As well, you can watch the replay to see all the times attacking sooner would have won it.

[gaetgu]

Another +1 for SC2. This game is great in and of itself, but it also punishes camping. If you camp you will be destroyed, so you have to build an army and fight. Games are pretty short (~20min) so there is a pretty quick feedback loop as well

[synicalx]

+1 for SC2, this game really punishes turtling especially when played online. Brood War is great as well but the dated visuals and difficulty involved in managing large numbers of units makes it a bit less friendly.