The wallpaper is one of the standard XBM images included with the X11 distribution (in OpenBSD, it's at /usr/X11R6/include/X11/bitmaps/mensetmanus).

The fonts are the Modern DOS collection (8x8 for the battery status, 8x16 for the terminal). The window titles use the classic bitmap Helvetica which has no antialiasing and gives it a unique "Vintage system" vibe.

I was going to give it a full CDE install, but the build guides don't seem to work right; I might switch to SparkyLinux for this machine because suspending fails just often enough to be annoying.