I have a puzzle in my planned game in which the player(camera) can only get past a door if he has found a hidden key. As it stands the player can simply walk thru the door or adjacent wall thus negating the puzzle. How can I fix this? How can the door(walls) be made to appear solid. Is it a coding problem or something that can be set in wed?

You can set a variable, for example found_key.

This one you set to 0, and change it to 1 when the player finds the key. Now you use if to check whether the player has already found the key. If he/she has, you open the door.

Therefore coding problem.

I know about setting flags but if the door and walls are not solid the player can just pass thru them. Thats the problem how do yuo make the camera incapable of passing thru the walls of my level?

use c_move that does the collisions-dection else, there is nothing that could be detected