Recommend Me A Game That Is. Low On Battery Usage And Preferably Downloadable

I'm going on a 12 hour plane trip with a very mediocre battery. I'm staring down Mercury Meltdown but I don't know about the battery toll. Yes iI have Echochrome and that's coming with me also. But, any games that fit those specifications would be a huge help to me. Also PS1 Games take up a fair bit of battery.

I do not know what your price range is but Persona 3 last a decent amount of time.