Well my first 'real' OS was a NetBSD 1.5; that I installed on my 486/40Mhz with 4 MB of memory. Linux Red Hat that I tried to run, was requesting to much disk space [250 MB - that was my beloved hdd] so I was forced to seek replacement for it. After some time I finally found it in NetBSD project.
For the first two-three years I doesn't use any X window manager instead normal console work was done by me, programming in shell/C, do irc botnet mange work, and some BSD research, and games
I ported the classic chess game from the Unix v.6 [these game also appears in various BSD distributions like 2.11/Reno/etc.] to my NetBSD box.
In fact If you go to /usr/games directory you will find many classic positions like:
wargames
or quiz.
Today I still run NetBSD.
Great OS. With real solid documentation; for instance:
http://www.netbsd.org/docs/kernel/