One of the things that goes into the blockchain is that you're subject to data bandwidth limits, so you probably want a hybrid on-off system.
Any software used would have to be designed more or less around Steem or whichever blockchain you want to use as your main method, though you could ostensibly have a client/server setup in which nodes only handle game-related content (which isolates you from general purpose networks and avoids spam).
IIRC it should be possible on Steem to make JSON entities that don't appear as posts but can be displayed in special ways; Steem Monsters does something like this, if I am thinking right.
Way Finder is what I was thinking of. I don't remember if that was the one I was looking for or not, but it's the one that I was able to recall today.