Espial.

In Espial, you play as Thomas Miller, a guy living in the city of London. At the age of five, Thomas was diagnosed with severe narcolepsy. Every time he falls asleep he dreams vividly of a distant world populated by human-like creatures.

Full Synopsis

One day in one of his dreams, Thomas is approached by one of the creatures and told to find a man named Chris Abbott, and to "release the secret". Thomas eventually finds Chris, and initially Chris claims to know nothing about what Thomas is talking about, but as Thomas goes to leave, he knocks him out.

Thomas awakes in a white room facing Chris, now dressed in a suit. Chris explains that Thomas doesn't actually suffer from narcolepsy at all. Thomas is an "exohuman". Separate from this world, he is able to interact with "Harvest", a universe parallel to our own. Chris explains that he is also an exohuman, and has mastered travelling between Earth and Harvest, unlike Thomas.

Chris reveals the building they are currently in to be his private exohuman research centre, where he has been studying the brain patterns of other exohumans in order to build a physical link between the two worlds, which will allow the transportation of physical objects and regular people (endohumans) into Harvest. He plans to teach the seemingly primitive Harvest natives everything about the technology on Earth.

With the help of Thomas, Chris completes his portal, and the both of them, along with a large amount of machinery and weapons, enter the portal and arrive on Harvest. After teaching the natives about Earth's advanced weaponry, the natives turn on Thomas and Chris, chasing them away from the portal and destroying it.

Chris, having mastered the mental transfer between worlds, instantly transports back to Earth, leaving Thomas stranded. Whilst running away from the natives, Thomas trips over a rock and knocks himself out. When he awakens, he is in the hospital wing of the exohuman research facility. Chris explains that the impact of him hitting the ground and the subsequent loss of consciousness transported him back to earth. Chris quickly transports to Harvest and back and finds that the introduction of weapons into Harvest's perfect society has corrupted it.

Thomas didn't dream of Harvest that night.