Are there other games nearly as good as this one, or is it all downhill from here?
Well let's just say you have started with one of the better ones. But you know, something than happens quite a lot when you have played a lot of lewd games is that you end up forgetting another great games with the passing time. When I talk about this my mind comes around "Dreams of desire" a game with freaking good renders, very good sexual scenes, overall good developed characters, hot girls and what is more importan a
GREAT and original story.
So I would say, no, you haven't reached the top and from now on it doesn't have to be a downhill. You have a lot to discover, like for instance if you like hentai based games, like I discovered recently with another great game "Ecchi Sensei" what kinks/preferences do you have and if they are represented in the games and of course a lot of great games.
And that being said I would like to recommend you a few that I like a lot and in my opnion are above the overall here, just so you can check them out: Dreams of desire, Ecchi sensei (with the dark mind patch), Depraved Awakening, Become a Rockstar, City of Broken dreamers, Dating my daughter (if you are into incest) The Elsa-verse (consisting on Dreaming with Elsa, Redemption for Jessika, Finding Miranda, Saving Chloe) Acting Lessons, Man of the House.
And the list could go on depending on your preferences. So don't worry, you will have a loooooooooot of good games to play and more coming in the future.