I used to get pretty much all the cheap humble bundles unless I was completely uninterested in them, so I have a moderately sizable steam library, so I know there's plenty of games on steam which would run fine on a chromebook. They are all either old or indie (even vaguely modern versions of Bejeweled will cause the fans to spin up on your GPU at higher resolutions) but there's tons of games which would work fine.
Which then brings us to... there's way more than 99 of them. Probably most of them are visual novel type "games" by now, but those games wouldn't suffer at all for running on a very limited PC. Was someone (google or valve I guess) preventing those games from being used for fear some kid might see hentai on a google device or what?