Install assaultcube by entering the following commands in the terminal:
sudo apt update sudo apt install assaultcube
Description:
realistic first-person shooter
AssaultCube is a first-person shooter set in a realistic-looking environment. The arcade-style gameplay is fast-pased and favours team oriented, multiplayer fun.
Homepage: http://assault.cubers.net/
Version: 1.2.0.2+dfsg1-0ubuntu4
Section: multiverse/games