It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

Delpino666: Are the keys still working? I haven't introduced any key at all and I'm allowed to play single and multiplayer without any problems at all.
The system works in such way, that only one key can be in game. So our generic key will work in multiplayer game, as long as no other player uses the same key.