Today I want to introduce a very different piece of software I have been putting together lately. It is a RTS (real time strategy) engine. I started playing with the idea as a time killer some years ago, kicking off the development with a fast version of the A* pathfinding algorithm backed not by a grid (as usual) but by a quadtree. Quadtrees make pathfinding super-fast because of their hierarchical division of space and their adaptive partition sizes. Even though I used visibility graphs to store the navigable nodes from one given point, quadtrees are also fast for checking the properties/elements of a position’s surroundings, for child nodes are always spatially contained in parent nodes.