Tetrobot and Co.

Excellent puzzle game, continuously bringing new ideas and head-scratchers along its levels. The movement is quick and smooth, the undo button makes the gameplay a breeze, the puzzle design favors simplicity rather than tediousness, and brings many satisfying moments. It's ten years old now but I played it through again with as much joy as the first time.

You play as a small flying robot that can absorb blocks and spit them out again. This looks like a platformer, but isn't. While blocks are affected by gravity, your character is not. Movement is tile-based and the action is almost turn-based. I have terrible reflexes, and yet I had no trouble except for one room (end of 6-3). There is a story about repairing robots and trying to find the main character's mentors, but it doesn't tie into the game that much (and says nothing about the slime bosses or keys). Length: 51 levels, a couple hundred puzzles, took me over 20 hours for 100% without hints. Pros: [list][*]Very intuitive game mechanics. There is an in-game journal, but it's only flavor. You learn everything you need to know about the blocks from the puzzles. [*]Nicely challenging puzzles. [*]Unlimited undo (called Rewind). [*]Level editor and Steam Workshop (408 user made levels right now). [*]The challenge is in figuring out what to do; doing it is generally fairly easy. [*]Works great on a touchscreen. [*]Graphics make it very clear what is in the room. [/list] Cons: [list][*]Somewhat buggy, especially if rewinding while things are happening. [*]No mid-level saves. [*]The stupid timing puzzle at the end of 6-3. [*]No tooltips in the editor. [/list] Score: 9/10