Lord of the Two Realms

A casual cultivator at the bottom of the world of immortality accidentally holds a "realm seal" and can travel between reality and the world of immortality to a limited extent. The higher-ups in the world of cultivating immortals forcefully opened the Heavenly Gate to escape from spiritual decline, but the process of merging the two worlds was knocked out. The protagonist relies on shuttles and inside information to get ahead, hoarding resources, grabbing nodes, and establishing rules, and finally turns a fusion land into his own "domain" and becomes the master of the world.