Schizm: Mysterious Journey is an adventure-genre computer game created by Detalion and LK Avalon and published by DreamCatcher Games. It was authored by acclaimed Australian science fiction writer Terry Dowling.
The game is reminiscent of the Myst series of games (especially Riven) in that the environment is rendered very realistically and in exceptionally high detail. Movement and interaction in the game is very similar to that in the Myst games. The background sounds are realistic and dynamic (for example, footsteps change as a character walks over different surfaces such as metal and stone, and echo when inside tunnels). The background music is very atmospheric and highly evocative.
A major distinguishing feature of Schizm is that the player can switch control between the two characters at any time. There are puzzles which require both characters to be performing actions at the same time before they can be solved.
Source: Wikipedia, "Schizm", available under the CC-BY-SA License.