As well as being a huge money-making machine, Zynga has also demonstrated a philanthropic side with various charity initiatives such as supporting earthquake appeals in Haiti and Japan.

Its latest scheme mixes viral promotion for its forthcoming CastleVille game with charity, however.

Wisdom of Solomon

The company is looking to get the game 5 million Facebook likes; a total that will unlock "exclusive game items" when it launches, as well as triggering a donation of $100,000, split between Direct Relief, Save the Children and Water.org.

'Likers' get to vote for their favourite charity, with the 'winner' getting $40,000, the second placed outfit $30,000, and the third $20,000.

If it hits its target, Zynga says it will also donate $10,000 to Direct Relief's Community Health Clinic, which is based in Dallas, where CastleVille was developed.

You can do your liking via CastleVille's Facebook page.