Fold Realm: building a world that only exists from one angle

Fold Realm is our first full game on Puzzlescape. Its rule is one sentence: two planes are joined only when they appear joined from where you are looking. Rotate the world and the road disappears; pull a lever and a standing page falls to become a floor. That rule is easy to state and surprisingly hard to build. Perspective games usually cheat with pre-baked impossible geometry. We wanted the geometry to be real, and the illusion to come from the camera.

So the renderer uses an orthographic camera with only two degrees of freedom. Under orthographic projection, sliding a point along the view axis changes nothing on screen — a fact we use in reverse: every level is authored by placing the next platform exactly one "view step" away from the previous one. At the intended angle the seam is pixel-perfect; a few degrees off, it is obviously broken. Connectivity is therefore not authored by hand. We sample the edges of every platform, project them, and measure how long two edges stay glued together. A corner touching a corner is not a door, so it does not count.

Two scripts guard every change. The first scans the whole camera space for each level and reports solvability, whether a level is trivial at its starting angle, whether the levers are actually necessary, and how wide the solution window is. The second one plays: it drives the engine headlessly, clicking levers, waiting for fold animations, turning the camera and walking to the goal — the same API calls a player triggers. Shipping twelve levels with that harness means "it should work" becomes "twelve out of twelve levels were finished by a script last night".