https://github.com/sobitcorp/Duke3DHD

Duke3DHD - HD and Widescreen in DOS Duke3D […]
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Duke3DHD - HD and Widescreen in DOS Duke3D

Requirements:

Duke3D (any v1.3 - v1.5)
A DOS/Win9x machine, DOSBox, or similar DOS emulator

Installation:

Download the latest release [here]
Extract into your Duke3D directory. Overwrite ART files at your discretion. Your regular DUKE3D.EXE will not be overwritten.
Run DUKE3DHD.EXE

Removal: To run Duke3D without HD textures, simply delete/move/rename the ART files and run your regular DUKE3D.EXE

Controls: Press F11 in-game to toggle widescreen.

Resolutions: The following are supported:

320x200
640x480
800x600
1024x768 *
1280x1024 *

*You need to manually edit ScreenWidth and ScreenHeight in your DUKE3D.CFG to set these.

The widescreen effect is achieved by playing on a widescreen monitor and letting it stretch the signal to fill the screen.

For advanced users: you can customize the widescreen ratio by manually modifying Widescreen and WidescreenMenus in your DUKE3D.CFG, where the value is calculated using (height / width) * (320 / 0.75). Set both values to 1 to revert to the default width:height ratio of 16:9.
HD textures

All but one of the upscaled tiles come from Phredreeke's Enhanced Resource Pack.

See the README in tiles/ for more information and technical details.
What's in this repo

DUKE3DHD.EXE - The modified Duke3D binary which properly handles HD textures and supports widescreen.
bastART.exe - ART file manipulation tool
COMDLG32.OCX - For bastART
src/ - Source code for DUKE3DHD.EXE
bastart/ - Source code for bastART
tiles/ - HD tiles and supporting documentation
screenshots/ - Scroll down