I made it into 2-21 before I ran out of energy. The battery recharges pretty fast, so not a hassle to wait. I used the included recharge and made it another 6 levels. It gets challenging once you start having to avoid the red lights that suck up the electricity. I will 3 star the whole thing, but I enjoyed the puzzles, the UI and the feel. The one issue is when you try to turn the beams, some energy is wasted as they move towards your finger rather than staying still. It's something to watch out for, but overall a solid game that is lots of fun and doesn't need an internet connection (I played it on a long plane trip).