On Android, there was no standardized controller support for a long time. The Bard's Tale should work with most compatible HID controllers on newer Android OS versions and devices, however, older ones may not work.
Additionally, make sure you have enough buttons to play the game on your controller - not all controllers have dual analog sticks, shoulder triggers, etc. and those are needed to properly play in controller mode. Anything with similar button layouts to an Xbox 360 or PlayStation 2/3/4 controller should have enough buttons.
We'd recommend the following troubleshooting steps if the game won't recognize your controller:
- Restart your Android device.
- Reconnect/re-sync your controller.
- If your controller comes with any software or requires an app, please install it.
- If your controller has any kind of mode switch on it (such as an HID switch or "mobile/PC/console" toggle), try changing that and see if the controller works.