Retro-style 2D scrolling platform shooter

 Dave Gnukem is an open source retro-style 2D scrolling platform shooter,
 inspired by and similar to Duke Nukem 1. It currently runs on Windows, macOS,
 Linux and various other platforms. It is written in C++ using SDL library and
 it features an integrated level editor as well. This game is not really a
 clone or remake, it is probably most akin to a parody.