The founder of Double Fine studios said that he receives daily requests for the sequel, but fans often do not understand how game publishing works.
"I mean I get a lot of, on Twitter or whatever, daily questions about Psychonauts 2. And I would love to do Psychonauts 2, I've actually pitched that to publishers several times and no-one has taken the bait so far," he told Digital Spy.
"So it is hard because fans often don't know how the business works, with the difference between a developer and a publisher, it's hard to explain that.
"I'd love to do that game, but I'd have to convince someone to just give me a few million dollars, that's all."
Speaking about doing sequels to previous games, Schafer explained that while he wasn't against the idea, it would "take the place" of making an original title.
"So if I did a sequel to any of the games I had before, it would have prevented one of the [new games]... if I did a sequel to Full Throttle there wouldn't have been Grim Fandango, and so on and so on down the line," he said.
"It's hard. But now we have multiple projects, we have multiple teams, one of us could be working on a sequel and one of us could be working on a new game. It opens up a lot of possibilities."
Psychonauts is a platformer featuring a psychic boy who can explore the minds and memories of others. It was critically acclaimed upon release in 2005.
The game was released on Mac last year, while the PC version was updated with Achievements and cloud save support through Steam.
Double Fine Happy Action Theater is out now exclusively on Xbox Live Arcade for 800 Microsoft Points (£6.80 / $10).
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Watch a trailer for Psychonauts below: