The Microsoft Store currently has these games available for free for PC:

https://store.steampowered.com/app/555000/GOAT_OF_DUTY/ -click add to account to get a Free Goat Of Duty PC Game Download on Steam.

https://www.gog.com/partner/stay_at_home -GOG has 27 Free Computer Games available:
Akalabeth: World of Doom
Alder’s Blood Prologue
Beneath a Steel Sky
Bio Menace
Builders of Egypt: Prologue
CAYNE
Doomdark’s Revenge
Eschalon: Book I.
Flight of the Amazon Queen
GWENT: The Witcher Card Game
Hello Neighbor (Alpha Version)
Jill of the Jungle: The Complete Trilogy
Legend of Keepers: Prologue
The Lords of Midnight
Lure of the Temptress
Overload (Playable Teaser)
POSTAL: Classic and Uncut
Sang-Froid: Tales of Werewolves
Shadow Warrior Classic Complete
Stargunner
Sunrider: Mask of Arcadius
Teenagent
Treasure Adventure Game
Tyrian 2000
Ultima 4: Quest of the Avatar
Ultima Worlds of Adventure 2: Martian Dreams
Worlds of Ultima: The Savage Empire

https://store.steampowered.com/app/406970/The_Uncertain_Last_Quiet_Day/ -click add to account to get a Free The Uncertain: Last Quiet Day Computer Game Download on Steam. ends March 8. It’s normally $15

https://store.steampowered.com/app/251870/Go_Go_Nippon_My_First_Trip_to_Japan/ -click add to account to get a Free Go! Go! Nippon! ~My First Trip to Japan~ PC Game Download on Steam. It’s usually $9.99. Ends March 6.

https://www.epicgames.com/store/en-US/product/innerspace/home – click the get button to get a Free InnerSpace Computer Game Download from Epic Games. Ends March 5.

https://www.epicgames.com/store/en-US/product/ -click the get button to get a Free Hyper Light Drifter PC Game Download from Epic Games. Valid today only.

https://apps.apple.com/us/app/pixelmator-photo-pro-editor – today only Pixelmator Photo for the iPad is free. It’s normally $4.99. –Update – was supposed to be for one day only but its still available for free.

https://apps.apple.com/us/app/bastion-by-supergiant -download the app and “purchase” the full game unlock within the app for $0.