So I'm not doing a full, proper review here (mainly because it's an unfinished game, and most of the time I prefer to reserve actual reviews for finished or abandoned games), but I have some thoughts I figured I'd share, since Nono is apparently following this thread now.
First of all, the gameplay. It tends to be a bit tedius and monotonous at times. Don't get me wrong, it has definitely improved since its early days. The food mechanic in particular is a hell of a lot better than it was way back when you had to spend the majority of your turns hunting just to keep your pets around, heh. So thank goodness that's changed. That aside, it's frustrating how you can go on a click-hunt for days at a time just trying to find the one sweet spot where there's a tentacle on the map, even with an assistant. Playing "hot and cold" can get old fast, especially when it doesn't seem to be entirely accurate or consistent. Those of us that've been playing this for a long while have kind of figured out generally where most of the old monsters hide on each map, and even then it can still be annoying- I hate to imagine how many newbies gave up and lost interest because they're at even more of a disadvantage. I like MsKris's idea of changing the map into hexagons to streamline things a bit- building on that, you could have already-explored tiles marked somehow, with a special mark to denote spots where a tentacle has been found, etc. You already have something like that for (admittedly still mostly unused) resources, so why not the beasties, too?
As far as battle goes: it's an interesting concept with promise, but still needs a good bit of work. One thing that irritates me to no end is the fact that, at least to some degree, it comes down to chance. Specifically, there seems to be no direct way to arrange which monsters end up behind another when you have a two-monster stack. This has lead me to unwinnable situations where the enemies reached my line before a monster pair could enter the battle because they were both too high-level and took forever to spawn. Had I been able to pick the arrangement myself, I never would have put them in there like that. So please, I beg you, let the player decide which monsters get paired up.
And another thing: putting certain actions behind a delayed release (nursing, scouting, etc.) was annoying, but understandable- the order, however, is off, IMO. You should absolutely be able to scout territories before invading them. The scouting mechanic was one of the most vital tools in earlier versions of the game, and should absolutely be knocked down to a much sooner availability.
As far as finding new monsters that aren't on the map, but rather a product of breeding: that's irritating, too. The whole breeding thing is time consuming and grindy, and rarely seems to go the way I want or expect. Even following the various formulae others have come up with, I still end up getting the wrong creature. There really needs to be a way around this. (Also, in the last version I played, it seems the Queens Nest was disabled? Which only further hampered matters)
When it comes to aesthetics- well, obviously that's entirely subjective, so take this how you will. In general I find the art style to be decent and the animations are reasonably good. For me, many sex animations tends to be on one extreme or the other: either I HATE it and click away in disgust asap, or I find it absurdly hot and go for that one frequently. As for the little stories some of them have, I'm similarly mixed on those. Not gonna lie, there are probably marginally more that I ignore than not, but there are definitely some gems in there. I would suggest adding a button to skip the stories if you've already gone through them with a tentacle of that type before.
And finally, I must add one thing that I'm sure you're sick of hearing by now, but it bears repeating: GALLERY GALLERY GALLERY!
-edited to add:-
You are too kind. So far the species that have events are: Dubois, Dolphy, Wolfong, Cirrus, Myrimidon, Harska, Beringarius, Butanga, Gritario, Nodder, Inker, Oturo, Bopbo, Weta, Slime Eye, Maratus, Scorpse, Skitz, Scrapper, Hopping Claw and Moth. Perhaps we can set up a section on the Tentacles Thrive wiki.
Please do! I'm sure plenty of folks would really appreciate that.