My son, Logan, loves the game Machinarium.
Our code for the final puzzle was a little different than the walkthrough. (Sometimes he gets frustrated with difficult games.. and gets all annoyed, overall it's pretty cute when he does it, but it can get hard to deal with after 30 minutes)
For a good part of the game, I refused to use the walkthrough. Then that bridge part, with the cat.. I was just lost.. Maybe it was just how many of those puzzles I'd solved that weekend, but I ended up being weak.. and going to look up how to do it.. then of course.. once you do it.. you can't easily stop.
1, 2, 3, 4, 1, 2, 5 was our code on the IPad 2.