Loyal Blog Followers Daniel and Joel and others have sung high praise for Snakebird.
The object is to get your snake/snakes to stretch out and get to the rainbow hole.
I have not solved many levels. Each one takes a lot of time, which I don't necessarily have to devote to a single game. Nevertheless, each level that I did solve had a fun 'aha' moment. If could focus on just 1 game for a month, it's be Snakebird. It's excellent.
https://itunes.apple.com/us/app/snakebird/id1087075743"mt=8

...