I do remember seeing one of their terms saying something along the lines of "similar games will count as one" for the purposes of installs+revenue, that or someone mentioning it. Can't seem to find it anymore, maybe they removed it? EDIT - Found one mention of it, "Games or apps with substantially similar content may be counted as one project", Unity probably went back on this one, as it's not listed on the FAQ right now
Though considering Pokemon Shining Pearl/Brilliant Diamond runs on Unity, I doubt they'd want to let such a high selling game go untaxed.