Epic games releases games for free every week (trying to get people to use their storefront over Steam). Some really great games have been free over the years. Epic pays the developers a fee, they list the game free for a week, and it drives people to use Epic. They're not crazy AAA usually (maybe 1-2 a year), but generally solid indies, less popular AAA, or old games that are very popular.
This year they've given away;
Football Manager 24
Dragon Age Inquisition: GOTY
Chivalry 2
Marvel's Midnight Suns
The Callisto Protocol
Wild Card Football
Marvel's Guardian's of the Galaxy
A Plague Tale: Innocence
And dozens of others.
Last year they gave away;
Fallout 3: GOTY
The Outer Worlds: Spacer's Choice Edition
DNF Duel
The Evil Within 2
Elder Scrolls Online
The Hunter: Call of the Wild
The Sims 4
Second Extinction
And dozens of others.