It's a textual adventure (some graphic embellish it, but is purely decorative and has no role in the game).
You give commands usually composed by a verb plus a noun (e.g. "go north", "examine desk", "drink potion") and are told what happens ("you cannot go in that direction", "there is a pen on the desk", "you feel reinvigorated"). You have to explore the locations, collect items, use them when appropriate and in general imagine how to overcome the various problems in order to accomplish the final goal of the adventure.
You are Amos Newton, young assistant of a scientist in modern days. Using a device of unknown origin, your mind has been transferred into the body of an alien being living on a different planet in future times. Controlling your host, you managed to help him.
Now you are going to use the device at maximum power, supposedly to transfer your own body along with your mind, hoping to find what happened to your mentor (disappeared after using the device at maximum power for the first time to study its effects).
You will have to survive, find the truth and return home.