The main thing im thinking about is what percentage of the coin will come via the game and what percentage via mining.
50/50. regular mining keeps the blockchain secure, stable and fast; while the game allows for fair broad distribution.
If it's able to be mined, why play? Having all coins released through play sets a fixed rate of release. in this situation, a premine may actually be a viable idea, with miners solving the blockchain for the TX fees.
Playing will help distribute the coins among a large audience, while you could play the english version , we can have +50 languages. The game will be a valid way to earn coins, while people doing the regular PoW via mining, keeping the blockchain, secure, fast and stable.
Think on Indian, Chinese, .... versions of satoshicode. "Airdrops" or Games, which one do you feel is more feasible?