I’ve backed a lot of board games. I would never back one that has not been throughly play tested, has the rule book basically finished (at least the text if not the images and graphic design), has a play through video, and ideally has some reviews of prototype versions from trusted reviewers.
And it's a good idea to apply similar ideas to early access computer games, which was my point. People will try sell you something that doesn't meet that bar, but you don't have to let them.
