This is an implementation of the Wikipedia game in the Elm programming language. It'll try its best to find a path between any two Wikipedia articles, sometimes with amusing results.
Have a play with it here! (｡◕‿◕｡)
Pathfinding is done in the browser using requests to Wikipedia's REST API. An unguided breadth-first search would be impractical, as far too many network requests would be needed.
The pathfinding algorithm is an A* graph search with a non-admissible heuristic. It attempts to guess how closely related articles are to the destination article. It may not necessarily find the optimal path, but it usually finds some path in a relatively short amount of time.