Your game idea needs a lot of technology that is not a game. The procedural stuff will be very hard to make, and might not actually improve the game. Maybe the seed you choose will start you in a vast wilderness, far from any cities or dungeons. Maybe your procedurally generated story will be boring. A lot of times, my Dwarf Fortress worlds will be terrible, with all the empires destroyed except the elves, and all the dragons and monsters killed. Nothing good. Just elves.
You will have to work very hard to be sure that each of the infinite possible worlds is fun and engaging. Maybe you should make it more like Diablo. The towns and NPCs are set by writers and map designers, but the wilderness areas and dungeons are more random. You could have a starting town that's designed by you, and have a couple places that are important to the basic story built like that, too. Then have the algorithm design all the other towns, dungeons and wild places on the fly. That way, you design the skeleton of the game, to make sure it has the right shape and does the right things, and then let the computer put the meat on, filling the world with new content every time you play.