I'm trying to set up some multiplayer games for classic shadow warrior using YANG. I told yang where to find the SW exe and I told it to use the DOS Box that comes in the shadow warrior directory that the GOG version installs. But when I launch like this through YANG, the game plays in a window instead of full screen, and there is no music.
How do I fix this?
I can hit alt-enter to make it fullscreen, but I'd rather have it launch in fullscreen.

Also, how do I launch the game in one of the expansions using YANG?

I occurs to me that for the most part, this is an issue with setting up Dos Box. I mean, the way the game launches normally it is using DosBox, and it has it properly read the CD for the audio, and launches in full screen. But when I use YANG, it isn't accessing all of the proper configurations for DOSBox to have those features.

YANG does let me point to a config file for DosBox, but when I tried to select a config file, I found there sere several of them. And when I tried the one that just said "shadow warrior" the game was borked; it wound up freezing on me, if I recall correctly.

So how would I get a config file for DosBox that would have all of these setting set properly?

Okay, I managed to find an answer on another forum, but I'm mentioning it here in case anyone else runs into this issue.

Here's the full solution I used:

In the Shadow Warrior directory, I made a copy of dosbox_swarrior.conf and renamed it "dosbox_sw_YANG.conf"

Open this file in a text editor, and add this:
[autoexec]
# Lines in this section will be run at startup.
@echo off
mount C ".."
imgmount d "..\GAME.DAT" -t iso

It should be placed just before the section [render], after the dosbox section.

In YANG, go to Settings>Source ports>DOSBox and check "Use the following configuration file as a base" and direct it to the file inside your GOG Shadow Warrior directory called "dosbox_sw_YANG.conf"

And it turns out that the game will launch in the regular version or the wanton destruction pack depending on which was the last version played through the regular GOG launcher, which makes it somewhat-easy to switch between expansions. It doesn't work with Twin Dragon though, so if anyone knows how to properly set up that mod, let me know.