As long as we are talking about old games that are still the gold standard, how is it possible no one has recreated the giant-god-monster and city management game Black and White yet?! That game was fantastic, and its premise so solid. It seems ripe for replication in more contemporary engines.
Peter Molyneux. Will Wright created SimCity and The Sims. Peter Molyneux created Black & White and Populous (and Fable, and Dungeon Keeper, and Theme Hospital, and honestly he had a really fucking good run until he disappeared up his own arse and then returned as a grifter).