I did manage to get BZFlag to run on the Nokia N800... "run" being the operative word. It is far from usable, and seems to only muster up enough power to get 1 FPS or less, though that was at 800x480 resolution.
Essentially what I did was install the Easy Deb package which enables you to download and create a debian chroot (technically, it was pointing to Ubuntu Jaunty packages).
Then from within the chroot I had to do the following:
Change my /etc/apt/sources.list to contain:
jaunty main restricted universe multiverse
Run an 'apt-get update'.
Then I installed the 'bzflag' package via apt-get, and then I installed the libgl1-mesa-swx11 (You can probably do them as the same step, but I didn't do that initially).
Then I set my HOME variable to /root/ by doing: set HOME=/root/
(It didn't like trying to write the config to the user's home directory since we are (and have to be, it seems) running the game as root.
Then I ran /usr/games/bzflag and bam, it comes up. I tweaked some settings in the game, like turning off texturing and adjusting some of the key mappings (setting the toggle radar and console keys to the top keys on the device, for instance, and getting a fast quit key set up). I was able to join a game and watch the slideshow go by...
Note that you don't get any keyboard interface on the N800, so you either have to edit the config manually to include stuff like callsign/password, or you can install the x11vnc package and enter stuff that way from a PC.
And for those wondering.. no, this is not a fake. But then again, it's not really much of an accomplishment either since it's not useful. Sure, I get bzadmin and bzfs too, but I already had that before by cross compiling them myself using Scratchbox. Still a bit interesting though.