Yeah I did the same and it quickly became very boring as I just held down the x button. This issue is largely due to the bounding box set on the sprite being far too small. As long as you avoid a bullet through the center of the sprite, it doesn't register as a collision... There will need to be some tuning as well as without the safe zone, it would take far too long to defeat the boss. All in all though, pretty decent considering it was made using construct 2...