You've really outdone yourself this time. When I first played Slave Lord it seemed like a good proof of concept, but it was riddled with issues, mainly the artwork and interface feeling extremely inconsistent. With the theme changing from a medieval setting to something futuristic, I was somewhat concerned the theme wouldn't feel quite as natural, but this installment is several leaps and bounds ahead of its predecessor, and I really can't overstate how good of a job you did here.
First of all, the amount of content in this game is staggering. Some of the scenes (particularly with the pixies and catgirls, or scenes with both Layla and Kaleena) do have some basic palate swaps, but with that aside there's still a gigantic number of distinct scenes present, and nearly all of them are drawn perfectly.
That being said, the H-scenes are probably the least engaging part of this game, believe it or not. The sheer length and amount of content present here make this a real adventure, and the backstory behind the characters makes it far more interesting to interact with them. The puzzles are mostly interesting (barring the really boring rock paper scissors minigame) yet the H-scenes are simple enough that they never break immersion. The secret achievements add an extra layer of completeness to this game (I especially liked that there was an entire scene hidden as a result of making the candle an unlockable.)
After seeing how much you've improved in virtually every area, I should mention that the audio in these games is straggling behind pretty badly. Whatever music you're using (I assume some free unlicensed music) gets repetitive with such a long game and oftentimes isn't really needed anyway. The dialogue, which comes in both sexy and funny flavors, would really pop with some voice acting, and the H-scene voices are really quite weak.
I have a few other minor nitpicks, but nothing major. The rest of my criticisms are generally directed at Flash's assets being a little more obvious than they should, with the line tool being pretty conspicuous in Scantor's map (Endoron looks gorgeous though,) the obvious use of the glow filter, the cliche and cheatable mouse mazes, and the style of animation not really suiting my style. For the record, my preferred style of animation happens to be extremely specific (Rock-Candy is the only animator here that seems to consistently hit the mark) and it would be extremely unfair to hold you to my (snobbishly high) standards, but I do feel animation is another straggler as you continually improve these games.
Main takeaways from this? This is one of the most thorough and complete experiences of an adult game that I've played. There are some vestigial quirks of your old works that still need to be revamped, but at the rate you're improving these are clearly temporary gripes.
As far as suggestions, you first order of business should be to get some voice actresses. This game has racked up a million plays and you have over 3,000 patrons at this point. You clearly have enough exposure to outsource your audio to some talented women so you're not stuck using crappy free assets.
My other suggestion would be to give the H-scenes a bit more nuance. This game's complexity is where its appeal comes from, but most of that complexity is focused on things outside of the H-scenes, and I think that's holding you back. Fekfek's game Rack does this by playing with player objectives other than reaching orgasm. Obviously the amount of work it would take implement that much depth into the immense number of scenes you have (as compared to the one scene used in Rack) would be a tremendous amount of work, but you could always limit each scene to one or two extra mechanics. Anyway, combining that kind of depth with the story and characterization that this already has would really pound the competition into the dust.
Keep improving this game. You're doing a fantastic job and it shows.