BitShares Toolkit isn't built on Bitcoin code. The code was written from scratch and is the first to implement Delegated Proof of Stake as a consensus algo. You are correct that it aims to be a fully fledged community / ecosystem rather than a minimal base implementation of a blockchain ledger. There is actually a project called BitShares PLAY (http://www.bitsuperlab.com/pdf/BitSharesPlayWhitePaper.pdf) that is in development which aims to be a decentralized game asset marketplace. Could possibly fit your use case well.

I don't know much about hyperledger other than it is designed to be solution agnostic and aims to be a platform for anyone to launch their own custom "private" chain.

if you are merely looking to use a crypto token for an in game currency, I would suggest looking into user issued asset solutions. NXT, CounterParty, and BitShares all allow you to register user issued assets which you can then distribute to accounts on each respective blockchain. Currently the cost to register assets in BitShares is pretty expensive but this price will be adjusted to be much less in a release slated for mid November.

The cool thing about BitShares in this case is that you can register human friendly names to send tokens to (using their TITAN technology). So if you are making an MMO style game, you could facilitate the exchange of currency by sending to directly to names instead of hash addresses.