Frozen Synapse, a great-looking indie simultaneous tactical turn-based strategy game (http://www.frozensynapse.com/) is available for pre-order for 20% off of the normal price. It's $26 for a two-pack, and the 20% off takes it down to $10.40 per person. Pre-ordering gets you instant access to the beta, complete with leaderboards. I've heard nothing but good things about it since they opened up pre-orders/betas.
I'm not quite sure when it ends, but a UK PC gaming site (Rock Paper Shotgun) said 1pm tomorrow, so I would assume some time around 7am central here in the states, or some time around there.