I've only tried withdrawing BTC once, so far, but had no issues with it - here's the transaction ID (it's from last week): https://blockchain.info/tx/bdc78ebc9cadc95cf67355c386a87473f0fbbdac5e44ac99bfd261f0f2980ee0.
However, for the sake of full disclosure, I should say I never deposit money/BTC in online games and have no intention of doing so with this one either (however much I may like the game); so, only my time is at stake here.