Before proceeding though, a few notes:
A: I WILL NOT provide the modded apk. No warez, means no warez. Thus why the guide. That way you have to get the file or Buy The Game Yourself...... (guess which one I suggest. )
B: This is a do it yourself project. Feel free to add, but all instructions are here. K?
And now onto the guide. I had the following when I did this on my Infuse 4G.
A rooted phone.
Root explorer (or other root file manager that can unzip and zip packages)
Signapktic (by our very own Stericson!)
1. Download and install original game.
2. Use root explorer to find the apk and extract all. (May have to move to internal storage, com.machineworksnorthwest.duke3d-1.apk)
3. Download this. ( http://www.multiupload.com/C61JX9RNYA)
4. Rename .bin file as duke3d.grp, all lowercase.
5. Copy into extracted folder, in assets folder and overwrite existing duke3d.grp.
6. Back out one level and remove the META-INF folder.
7. Package all into a new zip file.
8. Rename .zip to .apk. (mine was Duke.apk)
9. Sign with signapktic. (I used production key)
10. Uninstall original game and install modded.
Enjoy Duke3D as it was meant to be and how it could be released in the android market if chosen. This isn't Apple you know.