Stacking letters, might sound simple but try it yourself to see what a challenge that can be! The letters need to be places on one or multiple small platforms, and remain standing for a while. They also need to reach all the stars: they will become yellow when they are in contact with a letter. The more stable your tower is, the larger the chance you will complete the level. You can turn the letters any way you like, so think about what order you want to stack them, and how (upside down, laying on the side... it's all possible). Can you complete all the levels?
Use A/D or the arrow keys to turn a letter while moving it.