I love trains, so I made a little train network sim in Three.js. Build out a railway network across the USA, connect cities, theres also a NYC map (with actual landmarks!). It even has proper, real, multi-hop transfer routing (not just direct routes between points) and both a tycoon and a survival mode.

It is MIT licensed, completely free (no ads/purchases), and all saved data is kept client-side.

Just a little side project; I would love to see people's high scores!