Manually play Airstriker-Genesis with your keyboard in the OpenAI Gym Retro

Since it took me a while to find the answer to the question of how to play Airstriker-Genesis with my keyboard in the OpenAI Gym Retro, I wanted to write it down here - maybe helps someone else looking for this.

First, go here and use that code. It sets you up perfectly fine to play in the standard (non-retro) gym version. Problem is though, if you want to play Airstriker-Genesis by replacing this line…

env = gym.make('LunarLander-v2' if len(sys.argv)<2 else sys.argv[1])

with this one…

env = retro.make(game='Airstriker-Genesis' if len(sys.argv)<2 else sys.argv[1])

… you’ll run into the following error:

ap = a[self.num_buttons * p:self.num_buttons * (p + 1)]

TypeError: 'int' object is not subscriptable

After searching around for a while, the solution is very easy. Replace above line of code with this one:

env = retro.make(game='Airstriker-Genesis', use_restricted_actions=retro.Actions.DISCRETE)

Everything should just run fine by then. You can use keys ‘5’ and ‘6’ for left and right and ‘9’ to fire.