OpenRCT2 is the open-source adaption of the classic hit RollerCoaster Tycoon 2. Including online multiplayer, fast-forwarding and numerous bug fixes.
"OpenRCT2 is an open-source re-implementation of RollerCoaster Tycoon 2 (RCT2), expanding the game with new features, fixing bugs and raising game limits."
A project I never see great brought up enough so here's some love to a great classic game that's been revitalized by fans.
There's even a handful of original coasters (hybrid coasters, single rail coasters, and alpine coasters), although you'll only see them in custom scenarios. Still cool that they've added two "modern" coasters that didn't exist when the games first came out (the first two I mentioned).
They require you have the source files for the original game, which you can usually get for 1-3 bucks on gog or steam. Totally worth it for this masterpiece.
Re: openRCT2: you will need a copy of the original RCT2 in order to play it - it doesn't include the assets due to copyright. The GOG version's assets will work for it if you don't have the disc.
OpenTTD however, has its own custom open replacement assets, so you don't need the original game.
I can't let myself play OpenTTD anymore. It runs too big a risk of annihilating my sleep schedule. There's always some city that could really use some bus route optimization.
When I recently got my ultrawide, I thought what's the best game to utilize it? Then I found out this allows the game to support modern screen resolutions, so OpenRCT2 is great!