I'm not techy enough to know what Steem would do vs BTC as a game currency. BTC is likely to have some cool & fast payment channel stuff available by the time your game is ready. Keep your options open. Maybe you could integrate Shapeshift from within the game and you could then trade with an 'exchange NPC' or another player's avatar in a virtual marketplace. How cool would that be? Game items should definitely be blockchain tokens like Spells of Genesis is developing.
Maybe Steemit could be used for leaderboards, and as an alternate staging area for groups ready to go adventuring, raiding, etc.?
It all sounds awesome... I've been waiting for a game with real crypto. I'm sure you are aware, don't hold even a single customer satoshi on your servers... don't tempt The Man!
RE: Hi Steemit, I'm an ex-NASA network engineer, legendary member on bitcointalk, developer of bitcoinstarter.com, and creator of spacepirate