Altogether they’ve got 101 free open source apps and games listed. Most of it is games, but there are five non-games listed right at the end of the article.
I’m not too much of a gamer these days (beyond a bit of World of Warcraft). But I do like Extreme Tux Racer and SuperTuxKart. Both of those are a lot of fun, so check them out if you’re looking for a couple of cool Linux games.