For September 16th, looking at the Epic Games store website (link), the free games/or items they are currently offering for everyone are listed below, along with a look at what the next free item(s) will be.
- Spirit of the North, an Indie, adventure, single-player game is free right now until September 22nd.
- The Captain, an Indie, adventure, single-player game is free right now until September 22nd.
- ARK: Survival Evolved, will be free from September 22-29.
- Gloomhaven, a strategy/RPG/turn-based co-op, multiplayer, single-player game, that will be free from September 22-29.