To control Tupsu, simply tap his eyeball and drag it onto a surface that you want to stick it to. From there, the elastic tension created will automatically pull him toward that surface. Tap his eyeball again to release it and repeat the process. Since Tupsu's eyeball is so small, it can be difficult to grab and quickly maneuver around. Still, with the controls as is, the game is fun to play. And once you get the hang of the controls, you'll be able to pull off some nifty grab-release-grab sequences in order to "jump" from one surface to another. Getting this down will be key as you get farther in the game.
Each level is littered with floating islands. Some of them can be used as grabbing surfaces, while others are unstickable. The configuration of different surfaces will determine the difficulty of the level. Also, because Tupsu's eyeball has a very limited reach, you are forced to get creative in order to reach places high and far. Tupsu starts the game with a single eyeball, but as you progress, he gets more. As you can imagine, the multiple eyeballs enable you to propel Tupsu in more directions.
One nice feature is the Camera view. At any time during the game, you can hit the Camera view button to pause play and swipe around the level. Unfortunately, you can't pinch to zoom in and out the way you can with Angry Birds, but the swiping around is still helpful for larger, more-complex levels.
The first few levels of the game are quite easy and are meant to show you exactly what Tupsu is capable of and what his world has in store. After that, the game get surprisingly difficult, very quickly. Some levels have boxes that can be used as sticking surfaces, while others have blocks that reverse gravity. In Tupsu's world, there are a number of strange possibilities.
Tupsu's cutesy animation and silly-looking characters may draw you in, but its challenging levels and addicting gameplay should keep you coming back for more. Overall, this free puzzler is a worthwhile download.