At first I also had a problem with hitting the enemy, but I found that you have to turn on the vertical sync for the game in the graphics settings. Otherwise you will hit the wall, but not the enemies. Here is the link to the solution: https://support.gog.com/hc/en-us/articles/360009978773-Bullets-are-not-damaging-enemies?product=gog maybe it should be added to the info of the game or the game will get bad ratings.
