Having the same problem here, it worked earlier than I quit to do something else and when I tried launching again I got the "Open RCT2 Not Installed or Not Found!" thingEdit: Should probably note that I'm using the exe version of the Launcher
Using the launcher version, whenever I try to build a wooden roller coaster. I try to raise up the platform and click to place but immediately the game freezes and I have to stop the process to quit the game.