I'll be running a one-shot D&D 4th edition game on Sunday. I've asked the players to create 7th level characters of any race, but using only the martial and psionic power sources. This is a mashup of, at the very least, Psychonauts and Inception.
The players are MKULTRA operatives for the CIA in the late 60's. The project has discovered ways to project operatives (even those without their own psionic gifts) as avatars inside a person's psychic landscape, where they have a number of options for manipulating the target. Even the untrained reflexively resist tampering, and subtlety triumphs over direct action. Most agents are themselves targets early in their training, as the Agency hopes to uncover and correct dangerous psychic trauma and root out the seeds of disloyalty. It takes a target of strong but subtle will to conceal either of these for long.
Entering one's own mind, or the mind of another, is a risky prospect, as minds resist intrusion. If a psychic avatar dies, the agent suffers ejection back into the normal world and is overwhelmed with cognitive dissonance. Such agents must be relieved of duty until they can receive massive and complicated psychic surgery.
Fully-trained operatives traverse a different sort of space: that between the minds, where they track and infiltrate targets of interest. Most would characterize this space as a funhouse mirror of reality. The fears and dreams of the 50s and 60s have left indelible marks on the background psychic landscape, as people fear communist infiltration or nuclear annihilation and flee into the comfort of the science-fictional or fantastic: Asimov, Heinlein, Tolkien, Moorcock, and others. Avatars have come to reflect this in order to minimize the resistance they face in their work.
The Cold War against the Russians is only cold in reality; in the Elsewhere of psychic combat, it is most assuredly an open and brutal conflict. Just as the Agency can suborn a target through psychic intrusion, so can the KGB. Trust no one until you've been inside his head.