Not sure if anyone else knows (I wasn't aware until about a month ago), but Amazon Prime has a Gaming section. I get an email notification every so often, telling me about freebies I can get because I'm a Prime member.
So far there's not been a lot, but about a month ago I picked up Star Wars Squadrons, and yesterday, got Dragon Age Inquisition as well as Control. All for free. Well, not free, since you gotta pay for Prime, but it doesn't cost extra.