If you have a GOG account, occasionally GOG allow you to get select games in your steam library on GOG for free through GOG Connect.
New ones are up.
The available games include:
- Amnesia: A Machine for Pigs
- Banished
- FTL: Faster Than Light
- Grim Dawn
- Hotline Miami 2: Wrong Number
- Jotun: Valhalla Edition
- Kingdom: New Lands
- Legend of Grimrock
- Prison Architect
- Psychonauts
- Starpoint Gemini 2
- Tempest: Pirate Action RPG
- The Banner Saga