Thank you for your comment. I didn't do anything for the first two days of the competition and just slept, so I didn't have time to test the game. After installing the game, I noticed several errors, including the one you mentioned, but it’s too late now :( . Actually, there were supposed to be aliens appearing randomly in the game, and we could have destroyed them with our weapons. However, due to a major time problem while developing the game, I couldn’t add this feature.