Topic on PCGamingWiki talk:Game Article Layout
It would seem that way but not exactly. A game can be sold through Steam and not actually use Steamworks DRM - in which case you can run the executable direct from the steamapps folder and it won't use the steam overlay, etc. Additionally a game can be sold through Steam and use Steamworks for the Steam version only, with every other version being DRM-free or using different DRM.