You can rebind some of the buttons in the game, but the issue is that in the menus A and B are swapped, and this can not be rebound.
That might be handled automatically by the Gamepad API in SDL2, hence the game usage of the gamecontrollerdb file. You can create your own mapping and add it to the source of eduke32 before compiling, but it's kind of a long shot. See https://github.com/gabomdq/SDL_GameControllerDB, the Mapping Tools section.
Having the same issue in
Canna kit supplied power supply
image prebuilt from retropie website
Updated retropie setup script then updated eduke32 from binary then from source since binary upgrade didnt fix the issue.
@fuzzybat23 On first install, you will need a keyboard to configure your controller. You can do this by navigating to Options -> Control setup -> Joystick Setup -> Edit Buttons.
Once you have mapped your buttons, the axis mapped to turning will navigate a menu (this has probably already been mapped) and the button mapped to fire will select an item in a menu. I have not found a way to map Escape to a button so a keyboard will be needed to bring up the menu in-game.
Nam breaks duke3d and expansion packs now. I wrote on your wiki guide all about it. If anyone can find a fix I'd love to know what it is.
canna kit power supply
64gb sandisk class 10 micro sd card
upgrade from jessie to stretch, originally made from stock retropie image
Found A fix and is still applicable in retropie 4.7.1 :
So duke3d and all its expansion/custom levels run without issue until running 'NAM. 'NAM will run and continue to run every time you start it up but it changes the eduke32.cfg file located in opt/retropie/configs/ports/duke3d or (.etc/eduke32 in retropie 4.4.1)on its own and breaks Duke3d and all expansion packs till you manually modify eduke32.cfg selectedgrp field back to duke3d.grp. I've tried multiple times and nam breaks duke 3d and any expansion packs every single time.
To avoid this change the permissions on the eduke3d.cfg file so no one can change it. You can now run duke 3d, the expansion packs, and nam without anything breaking or having to modify anything after running nam.'
Sorry to necro post but I wrote this on a guide to install Duke3d on retropie and then when being forced to make a whole new image for to go from stretch to buster I couldnt find the post on github I originally wrote this on.