I picked up BioShock, but then I started playing the Sins demo to see if I should pick that up too. I'm not a huge RTS/strategy fan, but I like some and I like scifi games like Homeworld. Anyway, the first couple matches were rough. I didn't seem to be making any progress, compared to other similar games I've played in the past. So, I started looking up different strategies and trying different settings for the opponents. Just this evening, I played the first match that I finally started making progress on, not too easy, not to hard, and I was really getting into it, but then the demo time limit expired.
Today is the last day of the sale, so I'll probably pick it up. Otherwise, I'd probably get sick of playing the short demo and not be able to hold out for the next sale.