NOTE: I only played with a female character w/o futa because I'm gay and would rather not, so I haven't seen male responses to things and am only commenting on that female side.
Quite interesting; I've seen a few sandboxy porn games likely thanks to the success of games like Ai Shoujo AI and SDT, but also because it's a fantasy thing :P. I think this project has so much potential! Currently, it's super barebones, you can practically do nothing, and the character rig sometimes bugs, but even so it's really promising. Being someone who does a lot of sim stuff, I know how hard doing animation stuff like this is (unless I'm mistaken; I don't work with 3D much sadly). The characters have systems that are there but not implemented (again unless I'm mistaken), examples being the needs: hunger, thirst, social, and so on. It feels a lot like it's trying to be a survival colony style game but one where you do sexy stuff, akin to Ai Shoujo AI, but currently there's no AI, which may be intentional, I can't tell; if this is trying to be a full sandbox-like people playground than that's perfectly fine, it's just too early for me to tell :P. I've seen some of the stuff on Twitter and it's looking pretty good. I hope this one isn't abandoned like I've seen so many before.
As for the actual game: the UI is nice but sometimes gets right in the way, specifically, the sex menu zips around the screen, it would be nice to be able to pin it akin to how you can pin the dialogue. The sounds are fine at the moment; it's barebones like I said but I imagine this will get so much better with more variants and selectable sets (the variants are more important; and by that I mean having more sounds for the same things, if I'm correct on how the orgasms work, the sound is always the same--a slightly more intense moan--but it's hard to tell). Which brings me to the next thing; the feedback isn't great: the quivering is great, the moaning is nice (could do with some more types, maybe muffled as if the character is trying to restrain themself which I've found is common), the orgasms are my main gripe: they seem to last a single tiny moment and then the character is back to horny. There are no extended orgasms, there's no refractory period, and there's no visceral reaction to orgasms. At the bare minimum make the sex menu pulse blue or something when an orgasm is achieved, at the better end it could do with the character falling over or slumping if standing and it's a multi-orgasm, the character biting their lip, lots of people exclaim when orgasming, I don't think that'd work in this game but at least a more intense vocal moan or grunt would to wonders, additionally heavy and rapid breaths are pretty common. I'm not sure what assets the dev is working with but if they have a VA and the money, getting additional takes that're more intense will really help sell it.
Lastly, the mention of the octo-head guy was interesting; never showed up, I imagine because that system isn't implemented as of this version but it feels they will serve as a shop character or travel of some sort (I'm referring to the second island a little off from the main one). The lore bit is strange but that's something that'll have to be expanded or implemented at all before I can comment on it.
Okay; it may have sounded like I was bashing the game but really: it's a great base for something that could turn out great.
TL;DR: this is an unfinished but ultimately very promising demo of what could be with some more dev time and resources. I can't say I recommend this as a game yet but as a demo, it really works and I'll be on the lookout for updates. Also; apologies for the novel of a comment; I do this a lot ( ; -v-)y it's because I like stuff a lot, please don't think I'm trying to be mean or anything.
Good luck octolex! I hope this project works out and can get more updates in time: I promise you it's bound to turn out at least good with the baseline you've set! Cheers!