If you ever played RollerCoaster Tycoon(1 or 2) in your childhood, then you will know how amazing of a game it was for its time.
https://openrct2.org/
Anyway, OpenRCT2 is basically an open source version. One of the best features available is Multiplayer, and the support for dedicated servers. But also this game has a lot of cheat modifiers, such as unlimited money, and being able to change the operational status of some rides.
I would like to make a suggestion of an RCT event, maybe either a freedom style map (superflat), or maybe a build battle of some kind. I just want to see if anyone would be interested.
Thanks to @"StevenNL2000"#2 who also pointed out that you don't necessarily need to purchase the game to play it,
https://openrct2.org/downloads/demo