First thought: "Intriguing!" Second thought: "Ah. Hrm." The teaser trailer for IsoChronous, which you can see below, seems to want to explain its concept (which it doesn't quite manage) but also to obscure the actual game footage with floating concept art. Fortunately, a follow-up gameplay trailer makes the concept a little clearer with a glimpse of a battle taking place. That's fortunate because the concept is so neat. Here it is: "IsoChronous is an action strategy game for 2 players with a game mechanic based on time layering" What does that mean? Well, you will play out a battle, and then when it's over it rewinds and it plays again, only this time you add more units. Each time the battles plays through, it plays out differently because of new units interacting with those from the past. Past units remember what you decided to do in previous time layers, and try to play that out. The result should be some complicated strategy.
A pretty clever notion.