Before you say anything about EDuke32, I know all about it and that's all well and good. My question pertains to just the normal exe running in dosbox.

Didn't setup.exe have a screen resolution option for 1024x768 back in the old days? When I open it up from the GOG package and check the SVGA modes 800x600 is the max, but I could've sworn...

... and I see at least one video on youtube where the game is running that res in plain old DOS so I know I'm not crazy.

If I get bored enough I guess I could dig out my old hard copy of Atomic just to be sure.

Don't think so. I remember 800x600 being the max, even back in the day.

I only had it to 800x600 back in the day.

Modifying the game .cfg file should work.

Didn't Duke use the VESA drivers? If so, I think it should support 1024x768 natively, if the DosBox VESA reports it as being available.

You can make the game run in a higher resolution by doing the following:

Open the dosboxDuke3D.conf file with notepad.
Near the top of the file, make the output setting: "output=overlay"
Further down, make the aspect setting: "aspect=true"
Right below that, make the scaler setting: "scaler=normal3x" (You could also try hq3x or advmame3x if you want to reduce pixelization)
Save and close the file.

Open the DUKE3D.cfg file with notepad.
Near the top of the file, change the ScreenMode option to "ScreenMode = 3" (You can also try ScreenMode 4 or 5. If you leave it on the default of 1, the scaler options you set for DosBox will not work to increase the resolution.)
Save and close the file.

Now launch the game, and the screen resolution should be higher than 800x600. (Note: You do not have to change the ScreenWidth or ScreenHeight settings, you can leave those at 800x600, and the resolution will still be higher because of the DosBox scaler settings you changed.)

I second Jeffpiatt. I still have the original CD of the Atomic Edition and the max resolution was 800X600 when it was released.

at the time the build engine was coded 800X600 was the big resolution it was much higher than doom's only res of 320x200. there was 1024X768 when build came out.