This is great advice and your line of thinking is right along the same lines of what I had in mind (and currently in development). I had been watching spells of genesis and at one point was considering making SP a card-based game, but I wanted a true campaign that people could lose a full night of adventuring into.  I like that the Spells game has an element of ephemeral quality to it as an asset outside of their game.  

Leaderboard that's steem based, I like that idea, very original and has that community tie in. Wow, I'll need to chew on this a bit as I learn more about Steem/it.

Oh yeah, security is a big must, there shall be two-factor authentication, encryption, and hashing for the game functions. Each game roll is also currently probably fair as well, even though it's not gambling, I want to prove there's no "rigging" involved :D