Legendary. You're completely right, no additional seeds are needed. Because anyone building PRNG on Steem would most likely end up using Steem blockchain hashes for the seed values anyway, so nice work. This is really exciting.
I would love to create a basic UI for this contract if you wanted to publish it. I do wonder, is it possible for the contract to support dynamic tokens? As in the client can specify what tokens it supports, meaning you could create a dice game that supported rolling dice with any Steem Engine token.
that's definitely something that can be done, it requires a few tweaks but nothing major. The contract owner will then need to "top-up" the contract with any tokens so that people can play with them!