I am currently work on an open source game for linux, and I have been using the X11 libraries for graphics. I have chosen them because most other libraries require too many dependancies or 3d drivers just to play simple 2d games and other stuff like that. I have also chosen them because that was what the original project I forked it from used. The thing is, as far as I know, no one else is intelligent enough to use them for anything.
I was wondering if anyone else here has ever programed in X11, and if they would like to talk about their experiences.