My guess would be since they have an in the park VR experience now they have exercised copyright protection against other VR developers, and the app you are looking for was likely pulled from the store/stores.
That's a shame it would have been a lot of fun to try out, believe it or not I have not ridden a roller coaster in over 20 years, I can't because of health reasons, I remember when I was a kid I rode the Revolution in Six Flags Magic Mountain and I think also Colusus, I miss it so much and the only way I could ever experience it again is with VR, that's too bad.
Are you familiar with Cedar Point in Sandusky Ohio? They are known in some circles as THE roller coaster park. They have a VR app for iPhone and Android, you might try that....
