Omnipotence and omniscience would only be fun if you could willingly turn them off. You'd never be surprised by anything again in life, and that's no fun! There's probably all sorts of nasty truths out there in the universe I know that I'm much happier not knowing, especially about human nature. Plus video games would lose all their fun if you were omnipotent and didn't even have to try anymore!

There is a series of fantasy novels by SM Stirling that may interest you which starts with, Dies The Fire. (I always have to caution myself that it is not, in fact, called "Die In A Fire" as I usually coin it.) For reasons largely never really explained, gunpowder does just what you suggest -- and various other bits of physics don't quite work the way we expect them to (steam never quite does the trick, either). All our modern tech is effectively rendered useless ( ... )