Cut the Rope is a smartphone game that was really popular and soon made the jump to other platforms, including DSiWare and 3DS. I'd actually played a fair number of levels of the original game on an iPad a few years ago, but I've been playing it on an Android phone off and on for a while. I've been leery of physics-based smartphone games, since I'd played and hated Angry Birds when it came out, and at first I dismissed Cut the Rope as just being more of the same. A big part of that initial impression was due to the iPad touch controls themselves, which, not being a regular iPad user, I still find to be inconsistent and annoying.
The controls on the Android phone I was using worked perfectly well, however, and I got to quite enjoy the game. It's not completely mindless, and although there is a fair amount of trial and error with the physics, in general objects in the game behave in an understandable and believable way. Resetting a level is quick and easy, and the games introduce new mechanics at a regular rate. The aesthetics are cute and the game feels quite polished, and getting all the stars in each level feels fairly worthwhile. I got through a lot of "Season 1" of the first game (apparently there are three "seasons"), and although it's not addictive enough for me to want to blitz through all the levels in one sitting, I'm sure it's a game that I'll keep dipping into now and again. Not bad for a game that didn't even cost anything!