I finally got Neverwinter Nights to run on my debian system.A posting at The Linux Game Tome helped a lot:
* cp miles/* /usr/local/lib/
* cd /usr/local/lib
* rm libmss.so.6 libmss.so
* ln -s libmss.so.6.5.2 libmss.so.6
* ln -s libmss.so.6 libmss.so
or some other method of making it realize the miles libraries are there.
I had noticed before ldd nwmain that indeed the missing libmss was the problem and the instructions above fixed that problem. Though if you copy the lib to /usr/local/lib you should run the command ldconfig /usr/local/lib because that directory is not one of the defaults.
The game was still crashing but then I noticed that I was missing the most current patch:
Now it is working. A bit slow but that might be because I was trying to run with 64MB textures and a huge screen resolution and some of the openGL environment variables at maximum setting.
Addendum 03-12-23: I later learned what I should really have done – add the miles/ directory to the file /etc/ld.so.conf, (see man ldconfig). This file contains directories that ldconfig includes in the library cache besides the two default directories (/lib/ and /usr/lib/).