Cities: Skylines is a city simulation game that is complex enough to build universal logic gates in it. Using universal logic gates it is possible to construct any circuit including Turing complete machines. So, just like in Minecraft one can build a computer inside Cities: Skylines. However, it would be very complicated to build a fully fledged computer using these gates, so I will demonstrate a 4-bit adder instead. Everything is done in the vanilla version of the game, no mods or add-ons are required.
I’ve played a lot of Cities: Skylines, but I never thought something like this would be possible.