Ayayayaya,
I think the people who've played Roller Coaster Tycoon (RCT) will surely know that the game was just too awesome. RCT1 and its two expansions were pure fun fun fun. RCT2 was even more awesome as it shipped over pretty much everything from RCT1 and added more. More I tell ya! Then RCT3 came. POV camera ability so you can ride everything yourself! It was fun but it just wasn't the same feel as RCT1 and 2. The latest game, still in development I believe is even worse.
(Roller Coaster Tycoon World? Forgot exact name). Planet Coaster on the other hand was a much better game.
Anyway, The real question is: Don't you always wanted to build a park together? Now you can.
http://openrct2.org/The game uses host and client connection style. One person hosts the "server" and people connect. Obviously there are lots of bugs and desyncs going on, but the core game play is there. It is too amazing.
Enjoy creating your own park with friends, or perhaps a collaborative MotK park? Your call.
--Helepolis