He feels an open summons and lets it grab him -
It's immediately obvious something ominous is going on; higher gravity and a thin atmosphere, for one thing. A tiny sharp sun glaring coldly on an almost black sky without much air or dust to scatter the light. There's no living thing in sight to have done the summoning, either.
Maybe it's the fact of the circle being a huge and hugely complex fractal thing both familiar and alien in an odd way that probably warrants further study, and appears to have been laser etched deep into some kind of concrete like but smoother (almost glassy) material. The lines visibly reek of magic, a half invisible turquoise flame.
Or, it might be the endless line of almost identical circles extending like crops on a field along some kind of track, and parallel more tracks flanked by circles in one direction but just the tracks in the other.
The one single feature extending more than a millimeter over the flatness is some kind off vehicle on the same track as the circle, already too far away to make out any detail of and rapidly disappearing over the horizon.
Cam squints at the circle, and then shrugs and walks out of it. "Hello? Can I help somebody here?"
As he leaves the next outermost layer, there is a very short and high pitched beep, but otherwise nothing seems to happen.
Cam makes a little red flag to stick in his original circle in case he wants to find it again, plants it there, and goes aloft to see if there's anything else to be seen.
The light goes out for a moment, and then the bubble dissipates and drops him onto the floor of a featureless white cube of a room.
Cam thinks for a minute, then says, "You have until I finish my sandwich to say hello, before I start trying exotic acids and work my way up to black holes," and sits on the floor and makes himself a large sandwich and bites it.
"Ow," says Cam. He starts trying all the other languages he knows. "Can I just talk to somebody? Or go home, that would also be fine?" Repeat repeat repeat until he's out of languages. He didn't get any new ones with this summon, but who knows.
Another wall is covered in stuff like groups of dots each with one more and primes and fibonacci ones marked, atomic structure diagrams, and other standard attempts at establish basic concepts from nothing.
(OOC: If the surface of this wall is touched, it'll leave marks behind in the hologram, letting him draw/write, the others have other touch responses.)
Cam's hand is better by now. He thinks for a moment, then conjures up a copy of his computer from home, but under every layer of encryption he's ever heard of in case it's stolen away again because they don't want him to cheat on his prime numbers test or something.