Note! The original GShisen site seems to come and go. The server it runs on seems to be frequently attacked by site defacers. The sources I have here should build GShisen for linux/gnustep, although I can't be sure, as I haven't had a linux machine to test it on in a while. However, and earlier version can be found mirrored here.
Here you'll find the latest Mac OS X source and binary for GShisen, the first GNUstep game, ported to Mac OS X. The original page can be found here.