Nothing so advanced, I'm afraid. The Monte Carlo system just creates a thousand points (2d position and velocity), and simulates them at 1 generation per second, culling points that are unlikely and reproducing points that are likely based on observations (clicking chunks and hearing back "loaded" or "unloaded").
That sounds a lot like sequential monte carlo or a particle filter, which is a type of bayesian filter for inference. Really impressive what you did.
The write up actually does reference a paper on particle filters :o