Help needed!

Hi everyone!
I'm writing a game and I need lot's of good riddles. Not "funny" ones, but quite serious. The answer should be one (max 2-3, but 3 is ABSOLUTE MAX, better 1 or 2) word or number.
Any graphic (not using colors) riddles are also welcome.
Of course I need riddles with answers. They can be long, but the answer must be short (as said before).
AND difficult ones are welcome, because the game will start with quite hard riddles and then going up.

Post answers here or send me to my mail: [email protected]

Thanks!