Why isn't this game on Steam?
It isn't on Steam yet because Steam doesn't allow just ROMs to be sold. So I would need to build a standalone "exe" for the game to put it on Steam.
That being said, I am building a custom emulator for my next game, Super Sunny World, so that it can be sold on Steam. I have done tests and Witch n' Wiz will run in it as well, so I will likely bring Witch n' Wiz to Steam as well, once Super Sunny World is out.