I am able to play this on an IdeaPad U310 ultrabook without major issue. I had concerns that my Intel graphics would bottleneck the game, but was pleasantly surprised it runs as well as it does (albeit on a relatively native low resolution). There are times the game stutters, and I'm guessing frame rates are not stellar (I haven't run a count), but it is definitely playable -- and I'm loving it!
I hope other players find similar success on their lower spec rigs!
Specs:
i5-3317U (1.7 GHz)
Intel HD 4000 graphics
4 GB RAM
1366x768 (this low resolution may be my saving grace?)