An experimental cross-plattform-multiplayer for the theme-park-management-game Parkitect adds the possibility, to play the multiplayer with other platforms than Linux:

Experimental cross-platform multiplayer available

An experimental update for cross-platform multiplayer is now available for testing.
This allows all players to play together, no matter if you're using Windows, macOS or Linux.

Another huge update (v.13) called "Esparcidor de Estiércol" for Tropico 6 has been released for Linux on Steam:

Update (v.13) 'Esparcidor de Estiércol'

Fellow Tropicans,

Tropico 6 has just received Update 13 – Esparcidor de Estiércol. This update introduces the new ‘Flophouse’ building - providing, well... a roof (at least) for the poor - and the ‘Manure Spreader’, which should help put all that llama poo to good use.

For the free Raytracing-enabled version of the classic shooter Quake 2 the Patch 1.5 has been released for Linux on Steam:

Quake II RTX 1.5 PATCH

Hey, everyone! Today we're releasing v1.5, featuring the below features, fixed issues, and improvements.

New Features:

The Update 32 for the racing simulation Revhead has been released for Linux on Steam.

Date: 26-03-2021
Version: 1.4.7853

Dear Revheads

It is our Birthday Special Days, as you might know, Revhead turned to 4 years old. While our discount is still on for another week long, we are releasing new content as well. This is one of the best time of the year to grab your copy of Revhead!

The very huge Updates 1.40 for Euro Truck Simulator 2 and American Truck Simulator are now available for Linux on Steam.

The complete list of all changes (for ATS/for ETS2) is large, and include a completly new lighting system for the underlying engine and also revamped trucks and cities.

The update 1.5.4 for the free and relaxing Virtual Cottage is now available on Steam.

Among other things, it also adds new music and more weather:

Weather, savegame and to-do list
Hey Cottage Dwellers!

We were really busy with our other projects and there was no real time to work on the cottage. But finally it's time to bring a new update which introduces new features, quality of life improvements and some fixes.

The February 2021-Update for Civilization VI has just been released for Linux by Aspyr and is now availble on Steam.

Civilization VI - February 2021 Game Update Available Now

We’re excited to announce the February 2021 Game Update is now available to all Civilization VI players.