If I run the game in full screen mode, I can here the audio, but have only blackness, or a square of fuzziness in the top right corner of the screen. It works fine in a window if I hit alt-enter, but it's a tiny window. Anyone know how to fix this?

Yep, using "ddraw" finally worked. Thanks.

Sorry to respond to an old thread, but I was having trouble getting Battlespire working (Battlespire was loading in a really tiny box for me, with black all around it even though I have a relatively big screen) and changing to ddraw within the "dosbox_battlespire.conf" file was what fixed it, so thank you. That option can be found next to "output=" toward the top of the .conf file. I also set aspect=true but it was ddraw that fixed the issue for me.

(For whatever reason, "the Graphics Mode setup" file that came with the game from GOG didn't work for me at all, so I edited it in the .conf like that instead)