rugged vine
It is a project I've been working (together with a bunch of good friends) on a long while, some people from Slackers might remember it from a long time ago.
Subtransit Drive is a mobile phone version of a subway train simulator I've been working on. It is a digital twin type engineering simulator, meaning it recreates the trains on the level of individual components and calculates the overall behavior as a result of the digital twin simulation.
All of the train behavior is emergent from this digital twin model, allowing the train to behave just like the real thing, responding correctly and accurately to any possible user input - "you can push any button" type of a situation. This simulation runs using a custom framework and integrates with UE4.
The train is kept on track only by the interaction forces between the wheels and the rail, using a custom physics model I developed. The rails are not perfectly straight and result in complex 6-DOF dynamics. The train draws power from the supply infrastructure, so the running voltage in the third rail heavily depends on the current drawn by all the trains on the line, etc.
In addition to the engineering aspects, these subway trains have a considerable cultural impact in the region they come from, so we put a lot of additional work into recreating the cultural and art elements (environments, stations).
All the screenshots attached below are from the mobile version of the game. There are more screenshots here: https://subtrans.it/ (scroll down for more)
It's available to try out for free, with a purchase that unlocks additional content. Right now, it's only available for iOS, though an android version is coming soon:
https://apps.apple.com/us/app/subtransit-drive/id1636723806
