Amazing concept. It was great to see the details of the world when focusing in on a certain point. Really made me feel like I was a (buff) grandpa that needed visual aids. Traps and obstacles seemed to be placed with care such that one wouldn't be spending an hour to perfect a couple jumps to then be defeated by the next jump and have to spend another hour getting that next one down. The checkpoints were well placed such that I never felt like I was spending more time getting back to the obstacle than getting past the obstacle itself.
The story also matches the awesome art style. If only I could look as great as gramps without pants.