Check that your user account has permission to play games (put yourself in the game group).
KDE comes with lots of games. Under Gento get them with emerge kdegames-meta
Is a classic DOS game that has been ported to the Linux world.
http://Privateer.sourceforge.net/,
Figure 13.10. Privateer
Figure 13.11. Privateer
https://www.gog.com has good old games some are available for linux