TGV Voyages Train Simulator [Steam PC]
until June 2nd 10AM Pacific
https://store.steampowered.com/app/443910

Midnight Ghost Hunt [Epic Games PC]
until June 8th 8AM Pacific
https://epicgames.com/p/midnight-ghost-hunt

Tell Me Why [Steam PC] [Microsoft Store PC/Xbox]
until July 1st

This includes all three chapters when normally only the first chapter is free. Because a main character is trans, the game is not available in certain countries. If you already have the first chapter on Steam, you might need to claim through the direct package link instead of the store page.

Steam: https://store.steampowered.com/app/1180660
Microsoft Store: https://microsoft.com/p/tell-me-why/9nf83przk6k3

MiniTool Partition Wizard Pro is one of the best disk partition manager, which is designed for disk partition management, optimization, and data protection. It comes with so many powerful features that consists of a variety of useful tools and functions on disk partition management.

Amnesia: A Machine For Pigs [GOG DRM-Free PC/Linux]
until June 8th 11:59PM Pacific (before midnight)

Payday 2 [Epic Games PC]
until June 15th 8AM Pacific

https://epicgames.com/p/payday-2-c66369

The soundtracks are also available as always-free DLC:
• The Official Soundtrack
• A Merry Payday Christmas Soundtrack
• The B-Sides Soundtrack

Guacamelee! Super Turbo Championship Edition [Epic Games PC]
until June 22nd 8AM Pacific
https://epicgames.com/p/guacamelee-stce-7cdbc8

Alchemy Garden [Steam PC]
(551 reviews, 73% positive, trading cards)

Requires linking your Steam account (limited accounts don't work) to a Fanatical account and signing up for their email newsletter (unsubscribe here). Not available in some countries without a VPN. You'll also get a coupon for 5% off a Fanatical order.

https://fanatical.com/game/alchemy-garden

Goodie Pack: Everdream Valley [GOG]
"for a limited time only"

Contains wallpapers, avatars, coloring pages, and screenshots

https://gog.com/game/everdream_valley_goodies