I'd like to take this opportunity to acknowledge what I feel is the greatest FOSS reimplementation of a game engine: OpenTTD[1].

I'm sure many here fondly remember Transport Tycoon Deluxe, but for those who don't know it, imagine Sim City but only the transportation side of things (sea, air, road and rail.) The cities grow organically and you need to connect them with each other and industries dotted around the map.

It also has multiplayer which is really fun if you want to work either with or against others.

It seems the game is really enjoyable for analytical / engineering types, and I still love to play it after over a decade since I found it.

Nowadays, OpenTTD is available via most popular distros' package managers, along with free graphic and sound assets so you can jump right in[2].

[1]: https://www.openttd.org/en/

[2]:

  pacman -S openttd openttd-opengfx openttd-opensfx
  apt install openttd openttd-opengfx openttd-opensfx
  yum install openttd openttd-opengfx