It's a puzzle game. It's nice.
This game is mostly comprised of self-contained puzzle rooms (think Portal). There are a few bosses, lots of pointless enemies, and open areas, but it's mostly just puzzles that you solve and move on.
The humor and art are excellent, the puzzles are standard "push blocks, activate switches" and are fairly challenging, and the combat is boring Zelda-style whack-a-mole.
The game's main difference from other Zelda-clones is that it can be completed without attaining all the Zelda-esque special items. The special items can be attained in any order and the game can be completed with only 2/3 of them, with the player being able to choose which items to attain and which to skip. Most players will probably just opt for all of them, but the game activates in-game "achievements" for completing the game without a special item. It's a neat idea, though it requires repeating certain mandatory puzzles way too much between each play-through if a player tries multiple paths.
One play-through is about 4-6 hours, so don't plan a weekend around this game.