Are you bored, and do you have some basic knowledge about blender? Try the Unofficial Blender Riddle. It’s a riddle like not pron and currently has 11 levels, but more are on the way.
The reason why I’m releasing it now is to get feedback on the level of difficulty. So go play, and tell me what you think of it. Too easy, too difficult?
Edit: Currently there are 31 levels. If you wish you can take a shortcut to level 21.