If you're looking to blow off some steam or kill a few hours, these free and open source first-person shooter (FPS) video games for Linux, Microsoft Windows, and OS X may be just what you need.
Solving murder with Prolog. - In our company we usually have a fun quiz every sunday and this was one of them
Anki Overdrive Fast & Furious Edition drängelt im Test dank Überholmanöver, Single-Play-Modus, Waffen und viel Abwechslung die klassische Carrera Bahn mühelos von der Bahn.
OpenSpades is a super-fun "Open-Source Voxel First Person Shooter". I've been playing it for a while both on my GameOS desktop and under WINE on Linux. For whatever reason the upstream OpenSpades on github project had no Linux builds available for download, and I was lazy so I used WINE, which worked just fine.