Those of us who are not mining at home but still need our mining "fix" can now enjoy a virtual mining game at http://www.minerfarm.com!
"MinerFarm is a game that gives the Bitcoin mining experience on a virtual level, but it generates real Bitcoins that you can withdraw to your wallet. MinerFarm simulates the real life situations, hence you should create smart strategies in order to maximize your earnings. You can use the Bitcoins you produced inside the game for increasing your production capacity, or you can deposit Bitcoins to your account for purchasing miners. You can withdraw the Bitcoins that produced to your wallet anytime you want and use them in real life.
Rules are simple, every new player gets a free 10 Gh/s miner and a free 2000W power supply. Then those miner and device starts running automatically and produces Bitcoins.
Every new player joins to official pool and receive earning from each block found by this pool. In order to simulate real life, system finds a block at a random time and at least 1 block every hour. The pool members that found the block shares at least 0.001 BTC and this amount increases by time.
Every player receives an amount proportional to it's Hash power. Players can create their own pool, invite other players and increase their profits.
For further information about the MinerFarm, please click here to read our FAQ."
And yes, buying and selling miners, maintenance, cooling and services cost real BTC, but the user may also withdraw at any time. Looks like fun, so I thought that I would give it a try
Many others on the btctalk thread say positive things about the creator "aliser" so as for now I think the game is safe.