CasNum – A GameBoy ALU using only compass-&-straightedge constructions

Numbers are represented as points and arithmetic is built from five classical compass-and-straightedge constructions — addition by midpoint/doubling, multiplication via triangle similarity, and even bitwise ops implemented geometrically. There's an actual Game Boy ALU implemented this way (with a demo GIF) and a gnarly circle-intersection formula tucked into circle.py, which makes this part museum-piece, part engineering puzzle. It's delightful, slow, and clearly aimed at people who want to watch algebra get translated into geometry.