Matt is under some sort of mystical or alien induced slumber. The solutions of he other heroes is to enter his mind and bring him out. It's been done before so while not easy it's not impossible.

So select heroes enter and are automatically thrown out of game because Matt's memories aren't fill of sight. There is not visual cues for them, no metaphorical incantation of a path. Matt's mind is black, pitch black.

There is however a cacophony of sound, smell, touch and taste mixed and calling to them.

If they finally encounter a visual cue it's not quite right. Something is off about it. Like a picture kept in light too long.