Can't be done.
Didnt someone make a 2D Mario minigame before? I remember seeing a video of it, but its fail-binned now.
findclientbyname("yournamehere").player.setplayerscale("1 0.1 1"); tl;dr
I think there might be a third person camera node or something, but I'm not sure. There's already camera offset in scripts, and I'm pretty sure that camera angle is possible too, so this has a chance of being possible.
There is a topdown player though. Why not put instead make the camera on the side of the player instead on top and take away its ability to move left and right. Only problem would be turning around though.
what part of it can't be done the sideways camera?
Yes. Everything else is easy.