Wikipedia
AstroMenace
AstroMenace is a 3D scrolling shoot 'em up arcade game, developed by Viewizard. It is based on the C++ game AstroMenace which was released in February 2007 as freeware for Linux and shareware for Windows. Later was the game re-released as free software for Linux, Mac OS X, and Windows under the GPLv3 on Sourceforge. Content under CC BY-SA 4.0 license.
The game is basically a space shooter with the addition to buy new weapons, systems and hulls in order to improve your ship. You can earn money and experience points by destroying enemy aliens or pirates on each level. The experience points represent the "score" which makes your skill comparable to other players.