To earn btc by playing you can play with Huntercoin (HUC) and exchange the coins using Poloniex.
https://bitcointalk.org/index.php?topic=435170.0Welcome to Huntercoin – A Human Mine-able P2P Decentralized Crypto Currency & Game
Huntercoin is a Crypto Currency similar to Bitcoin . – see
https://www.bitcoin.orgUnique:
P2P Decentralized (severless) Massively Multiple Player Online Game
Game inside the Block Chain
Human Mine-able CryptoCurrency
Features:
Instant Peer-to-Peer Transactions
Global
No or Low Transaction Fees
No Central Authority or banks
Secure
Open Source
Some differences with Bitcoin
1 minute transaction times
Human Mine-able – Mine with your mind.
Machine Mine-able – Dual Algo – SHA256 (like Bitcoin) and Scrypt (like Litecoin)
Merge Mineable – With Bitcoin (and other SHA256 Coins) and Litecoin (and other Scrypt Coins)
P2P Decentralized Massively Multiplayer Online Cryptocurrency Game – MMOCG
Based on Namecoin – The First Altcoin, and still the most innovative. Allowing things like decentralized DNS – check out
www.namecoin.info and
www.namecoin.org