https://itch.io/games/platform-linux.
LGDB
The Linux Game Database (LGDB) has more than 2,000 games available to
download, along with emulators, tools, and a web forum to discuss games,
gaming, and Q&A with other users. You can find the games list at
https://lgdb.org/games.
Game Jolt
The games on this site are all indie games, meaning they were created by
individuals or small companies. Like the other sites, this site offers many
cross-platform games. You can find a list of the Linux options at
https://gamejolt.com/games/best?os=linux.
Installing Games in Ubuntu
In this section, you learn how to install some of the popular games for
Ubuntu, all of which can be easily installed from Ubuntu software
repositories. Alongside the usual shoot-’em-up games, you’ll also find one or
two strategy-focused titles.
Warsow
Warsow is a free and fast-paced first-person shooter (FPS) game that is
available on Windows, macOS, and Linux. Members of the Ubuntu
community have packaged the game and make it available directly and easily
for Ubuntu users from the software repositories. The game involves moving
quickly, grabbing power-ups and weapons before your enemies do, and trying
to plant a bomb and steal your enemy’s flag without anyone seeing you. You
can jump, dash, dodge, and even wall jump your way throughout the colorful
3D environment. Figure 8.2 shows a game just getting started, with lots of
weapons, platforms and ramps, and power-ups in sight. There are many other
FPS games available, such as Alien Arena, Urban Terror, Wolfenstein: Enemy
Territory, Smokin’ Guns, Nexuiz, World of Padman, and Cube 2: Sauerbraten.