I saw Game X in a Heaven Studio remix, but I can't find it in the editor/I’m getting “No Game” when playing a chart!
It was probably a game from the Nightly build! It's a special beta build of Heaven Studio you can download from our Github Page. In it, you can find games in progress for the next release! Be advised, though - games in the Nightly build are liable to be unfinished, unstable, and in a state of constant working and reworking. Don't say we didn't warn you!