If you're looking for some interesting books about Linux, you might like the Humble Book Bundle: Linux by Wiley 2019:

Pay $1 (about €0.89) or more to unlock!

Linux Essentials
Second Edition

Ubuntu Linux Toolbox: 1000+ Commands for Power Users
Second Edition

Linux All-In-One For Dummies
Sixth Edition

Beginning Linux Programming
Fourth Edition

Pay $8 (about €7.10) or more to also unlock!

Trüberbrook, the mystery adventure with handcrafted scenery, is now available for Linux on GOG and Steam!

»Trüberbrook« is a thrilling mystery-sci-fi adventure game.

Enjoy an adventurous vacation to a 1960's parallel universe! A Sci-Fi-Mystery Adventure Game with handmade scenery.

A new (paid) DLC for the management-game Railway Empire is now available for Linux on GOG and Steam: Germany.

New scenario - Patchwork (1850 - 1870)

Map expansion: Germany (available in Free Game and Sandbox modes)

10 historical engines such as the Adler and the Rhein

For the strategy game Hearts of Iron IV a new DLC called Man of the Guns is now available for Linux on Steam.

The second huge DLC for the RPG Pathfinder: Kingmaker called Varnhold's Lot is now available for Linux on GOG and Steam!

The new DLC "Gathering Storm" and a (5.6 GB) huge update to Civilization VI have been released for Linux on Steam.

In Gathering Storm, the second expansion to Civilization VI, the world around you is more alive than ever before.

At HumbleBundle you can currently get an very interesting Bundle for strategy-gamers on Linux: the Humble Paradox Bundle 2019.

From $1 on you'll get:

- Age of Wonders II: The Wizard's Throne
- Darkest Hour: A Hearts of Iron Game
- Magicka 2 (Linux native)
- Crusader Kings II (Linux native)

If you pay more than the average (currently at $6.10) you'll also get: