At all possible to do so? I've been trying with no luck. I attempted Alt+Enter, -Window, F4, and also DxWnd.
I'd like to stream the game on twitch but I am having issues doing so because Xsplit won't detect the game source when it is running and if I just capture the desktop and let it run full screen, its a black screen.
I also can't force a window.

better late then never - use a glide wrapper that allows windowed mode, like dgvoodoo.

as long as you set up the wrapper to run in a window, the game should run windowed. see the wrapper readme and the configurator.

Apologies for digging out old thread - but I'm also looking for possibility to play the game in the window. I've tried with making adequate settings with dgvoodoo and using it, but game is still launching in full screen (splash screen of dgvoodoo is visible!).

I've tried with dxwnd, but it also didn't help, game is still running in full screen.

I made it work in Windowed mode using Glide but it's not optimal because the mouse is not fully captured and in order to play you need to leave the window on the left side or only the right half of the game will be active.

Thanks Masterneme, a bit later I've asked DxWnd developer about it and he made config files for both base game and add-on (GOG version), which are both working absolutely fine. But thank you for sharing an additional way, just one question - by "Glide" you mean some additional software, or config file? Because in config I see only Directx and 3DFX options.

P.S. I forgot to post link to the topic where DxWnd Developer has posted both config files for this game (for DxWnd):
https://sourceforge.net/p/dxwnd/discussion/general/thread/b81c72f3d3/#516b

Glide is the name of the 3Dfx driver. The main difference is that it gives you texture filtering but as I said is a bit finicky. I also noticed that the music doesn't loop which as very annoying, do you have any problems with that?