Alexey Pajitnov (designer of Tetris) and Markus Persson (designer of Minecraft) were kidnapped because they were supposedly collaborating on a new game. Instead they were working on a miniature robot that was a blend of their two computer games. Tetrobot was activated in their absence and had to go rescue them from "The Boss." Definitely cliche.
As Tetrobot, you start out only being able to jump but quickly get a drill attachment. With this drill you are able to drill and collect certain blocks in the level, similar to Minecraft. Throughout the game, a couple of upgrades are added to Tetrobot to allow it to drill and collect different types of materials. With this collected matter, Tetrobot can regurgitate the blocks onto the paying field following a couple of rules:
1) The first block must be anchored to the level. It cannot just be put into mid-air. Subsequent blocks must be attached to blocks currently being placed.
2) Groups of four blocks must be placed. No more - No less. This creates "Tetronimos" I-J-L-O-T-S-Z.
Collecting and building platforms to get through the level is the goal. There are couple other things such as undrillable blocks, falling blocks, slimes and TNT. Each level also contains a Treasure Chest. Collect this chest and bring it to the level and you collect the "Block That Matters" for the level. The blocks that matter all pay tribute to different games.
Finally, every level has a star available. If you finish the level with a set level of blocks in your inventory you get a star, i.e. finish using the minimal number of blocks left on the board. Finish at the minimum get a gold star. Finish below the minimum and get a green star.
Rescuing Alexey and Markus will probably only take 3-4 hours. One of the Steam achievements is to complete this part of the game in one session. However, to get 100% (all the BTM and stars) will take significantly longer. I have played about 15 hours and still have 16 stars to collect and 14 bonus levels to complete. This is a fun little puzzle game that can provide a casual distraction to full out rage quit.