So there's no much games outside this site?
It's not because there's no games (outside of rule 7 and language) that aren't allowed here, that all games are present here. There's tons of games outside of this site.
Aren't here: 99% of the Asian adult games from the 90's, 100% of the western professional adult games from the 90's and early 00's, 99% of the 00's and early 10's indie production, and 100% of the none English (translated) games.
As for the games present here, there's probably less than 20% of the transforming games, and I doubt that there's more than 70% of the English translated Asian production. Are also missing all the games that started less than 6 month ago and haven't yet made it outside of the author inner circle of friends.
It's just a wild guess, but you can expect that, talking about the whole games production, for each game present here, there's 10 or more games that are not present here. And if you limit to the actual games production, there's probably only half of the games that are available here ; 90% if you limit to the Western side of the community.