Nice concept but I encountered some problems: 1) Sometimes the "enemy" was generated in front of me which makes it really difficult to start 2) It would be much easier if when I took a crystal you would hear some sound effect because sometimes I can't understand whether I caught it or not 3) Some crystals almost spawn inside the walls which makes it difficult to get them 4) I don't know if it's intentional but you can shoot with the left button