I don't think there are many -- and my GOG forum searches were fruitless -- but are there other DRM-free stores online?

I have heard Zoom is DRM-free... is Matrix Games' store DRM-free? Any others?

1. GOG
2. Zoom

kbnrylaec has provided a list of other stores here: List of DRM-free video games digital distributors

Last updated Feb 24, 2021 so the information should still be current.

Just be aware that in some stores, only some of the games are DRM free and that the list includes sites where a client is required to download the game. (But once downloaded, it can run without the client)

Also worth noting one of these stores, Playism's, is closing on the 24th, so if anything there catches your eyes, make sure you go buy them before the buy option is gone.