Management and business simulation game OpenTTD is coming to Steam in April, an expandable and beloved classic of the tycoon genre. In OpenTTD players run a transport business, moving passengers and cargo via water, rail, air, and road from place to place to develop a world and get rich. It first started in 2004 as an open-source remake of the 1995 game Transport Tycoon Deluxe and has been maintained and expanded ever since on account of its open-source nature and simple moddability.
Prior to this release, OpenTTD was only available via its dedicated website.
OpenTTD is a very well-regarded game among fans of transport and management tycoons, focusing on logistics and spatial placement on its square grid. Despite its simple appearance it's actually a rather complex simulation, with trains taking into account things like acceleration and torque as they move up slopes.
It's also very simply moddable, with community-made extensions available in-game for new vehicles, industries, and scenarios. There's even stuff like cat trains, space trains. It gets weird and it gets excellent.
You can check out OpenTTD on Steam, and wishlist it before its April 1st release.