😋I recommend to you the sci-fi-doomsday crisis novel "Saving the Crisis of the Other World". The plot matches the information provided. The main character, Carefree, transmigrated to another world and faced the crisis of monsters and zombies. He fought monsters and dropped equipment along the way. After returning to Earth, he discovered that the Earth was terrifyingly deep. He discovered that the Moon was actually a spaceship. Earth's ancestors had once fought with the Moon Alliance, and both sides suffered losses. There was actually a Spiritual Realm on Earth? The solar system also had a moon? There was also the parallel Mountain and Sea world! The protagonist also carried a laser gun and the Zenith Sword with him, but the Zenith Sword was sealed by the Radiant God Cult. I hope you like this fairy's recommendation. Muah ~😗