In Love Apartment, I used a cheat to develop the Multiverse Gate.

Zhang Yu thought he had been reborn, but after living there for over ten years, he discovered he was in the world of "iPartment." An accidental discovery led him to use his transmigrated talent to develop a portal to other worlds, resulting in the appearance of characters like Dongfang Bubai, Lü Bu, Hattori Hanzo, and those with the Suzaku bloodline—all oddities from human history—in "iPartment." It's a slow-burn story; he didn't transmigrate immediately. ...