Connect a Bluetooth keyboard as a game controller to an iPad?
Solution 1:
Go to settings - accessibility - switch control, then set up switches using external devices and use the keyboard buttons. Then create a recipe and add all the buttons as taps on the screen where the buttons are located. To make it easier, set the preset recipe as your controls, and when you triple press the home button it will turn on the keyboard taps.
Solution 2:
You can jailbreak and then use the Cydia app controllers for all.