KGoldRunner is the best game for me offered by KDE. It offers very good gameplay (tests your reflexes, your brain and sometimes even your patience), coupled with very good default theme complemented by a few more good themes.
No best way to introduce than the game’s documentation itself: -
KGoldrunner is an action game where the hero runs through a maze and dodges enemies. You must guide the hero with the mouse or keyboard and collect all the gold nuggets, then you can climb up into the next level. Your enemies are also after the gold. Worse still, they are after you! They will kill you if they catch you!
The problem is you have no weapon to kill them. All you can do is run away, dig holes in the floor to trap them or lure them into some area where they cannot hurt you. After a short time a trapped enemy climbs out of his hole, but if it closes before that, he will die and reappear somewhere else.