I love the artwork!
The animation of the rock and chains on the title menu and during the game is very nice.
I just played the 1 player version, and I guess the 2 players version is a lot more fun to play. To make the 1 player version a little bit more fun, I guess you should work on the AI of the enemies which tend to just glue themselves to the player and keep pushing them, which is easily defeated.
The overall feeling of this game is very nice though.
Kudos