Bitzfree is a "cloud mining" game, interestingly, they give opportunity to hack other users' account and steal 10% of the victim's GHs.
They have developed a Free Bitcoin Cloud Mining server, don't expect high earnings, it's a combination of the faucet and cloud mining concepts, like a game.
You start with 20 GHs SHA-256 cloud mining as a starting bonus and you can earn bitcoins proportional to your GH/s amount like a classic cloud mining server.
You can change your mining policy at anytime. For example, choosing "Cheaper GHs" will decrease GHs price with 20%, therefore choosing this strategy will be wise before purchasing GHs.
GH/s power can be purchased with bitcoins and bonus points which can be earned for every login.
Enjoy !