Close to very good. Although it's a pretty standard night crawling game, it does many things right while also having some problems.
+Pros:
Art: Excellent pixel art, it has been quite a while since I've seen some good-ass pixel girl. Only real problem is the animation can be a little bit better, since fucking her doesn't bounce her up and down, so it feels really stiff. I know animations are hard to do and all of that so it's forgivable.
Amount of H-content: lots of upgrade that gives you lots of things to do on the girl, really fun to see some of it. The multiple night end art and two endings (one for normal, one for pregnancy, though they are almost identical) are pretty fun to find using different combinations of actions during the night.
Sounds: really good sound design overall. The heartbeat, the touching, etc. really helps improve the atmosphere.
Gameplay: Smart gameplay choices. The upgrades give you lots of advantage, and actually requires some brain to choose unlike most touching game. I like the choice between single action for your first nights, and continuous actions for later nights once you're not threatened by her sleep bar. I also like the different type of night end, where it gives you more (or less) points based on the type of end.
-Cons:
Transparency: So the game doesn't exactly always tell you how it works. The extend night duration upgrade, for example, doesn't actually increase from three to four minutes, it actually slows down the timer. Another example is the bondage upgrade, which it only tells you that you can tie her hand. How do you activate it? Well it's on the bed and all but you can't click on it... until you spread her legs and boom, it's actually the whole bondage set. One last thing, is how the game multiplies your points at the end of the night, but will not show you how much points it multiplied, or if it was multiplied at all. This cause me to not realize that a perfect night gives you way more point until much later. It can be very hard to figure out what each thing does, since the game only vaguely tell you what it is, and that frustrates me.
Progression: This game requires too much grinding for a touching simulation game. Most of the time, these games are short and doesn't require too much thought to play them. This one? Takes wayyy longer than it should. Of course, getting points and min-maxing the game is easier as you go, but again, like I said above, the game is not very transparent so it's somewhat difficult for you to min-max at all.
Lacking some features: I think proper free play mode would be pretty nice, since after all, the night will still end after some time. Customizing how much you cum on her and all of that inside free play mode would have also been an awesome addition.
Overall: I think Night Adventure is great, just that it's a sloth to fully get through, and can get boring very quick. If only the game's progression was faster, and there are clearer descriptions to upgrades and mechanics in the game, then it would have been a 5 star from me. 8.5/10