The rumble (vibrate) option isn't working for the GBA retroarch cores on multiple emulator devices. I have set "Rumble: On" it in the options screen and the game restarts, but with message "A GB Player has not been detected. Rumble set to fallback mode. This requires a compatible emulator or flash cart." I have retroarch core options -> Input & Auxiliary Devices -> Game Boy Player Rumble option set (on mGBA-rumble core)
I'm able to play "Drill Dozer" on the same retro handhelds with the rumble working normally. Not sure why rumble is being disabled automatically on this game\?