There may be some spoilers in this review, but the game is free, so there's really no reason not to play it before reading.
Powerhoof's Alluvium was not at all what I expected going into it. From the thumbnail with the bright colors and flying plane, I thought this would be some sort of futuristic vaporwave adventure. The bright, vibrant colors of the game itself were on point to my initial expectations, but as for the story, maybe its lesson is that you should always be prepared to have your expectations subverted.
In the case of Alluvium, subversion of expectation leads to surprise after surprise as the plot marches forward. Even with all these twists and turns, I did not feel distanced from the story at any moment as Powerhoof's characteristically great storytelling shines through.
Normally point-and-click adventures are text heavy, and while I don't mind that, other people might. Alluvium's solution to this is exciting and at times emotional voice acting from Adrian Vaughan, detailing Ian's internal thoughts and external conversations, his potential deaths from wrong moves and his return to reality, showing the last action to be in Ian's imagination (a concept that I've only seen a few times before and absolutely love rather than a game over or simply limiting the player's actions to the right choice).
Sally Beaumont portrayed Anna's creepy cannibalistic touch of insanity excellently. Speaking of, cannibals on desert islands are usually portrayed as otherwise uncontacted natives, but a corrupted crew drunk on mysterious berries, attempting to corrupt the last (debatably) sane crewmate is a thrilling change of pace. Ian's reentry into insanity and his resistance to it as he approaches the former campsite harkens back to the subversion of expectations when first setting out on this adventure. Ian's disgust and revilement of the rotting flesh of his comrades seems to show that he is reformed from his cannibalistic ways, which is confirmed in his moment of self-sacrifice as he destroys the dam with the (seemingly) last remaining cannibal atop it.
After the credits, I was left with just one question: Was the Russian captain truly there, left behind by his crew? Or was it perhaps just some random person that Ian hallucinated was the captain?
The story seems complete and self-contained, but the more I keep thinking about this game, the more ideas I have for a continuation of this island's tale. Perhaps Ian is flushed out to sea, but washes back ashore, awakening to find a cannibalistic society of the crew and their progeny that worships the evil fruit. If Ian is truly dead, perhaps the Russian ship comes back with someone to investigate, and that detective would be the main character. The main character would seek to put a stop to the society's atrocities - farms where humans are raised as livestock, prisons where people are kept in pits, and fed human flesh, but no berries, so they regain their sanity, but are driven mad again as they're forced to eat their fellow man. Perhaps the story ends with the main character blowing up a volcano on the island, destroying himself, all the cannibals, and all the berries in the process... And in a post-credits scene, a few stray berries would be seen floating across the ocean...
Of course this is just rambling at this point, and I'm much more eager to see a continuation of the Telwynium series, but there is definitely room for a series of two or three games to be made out of this one. Perhaps someday after the Telwynium series is complete, we'll see a return to Alluvium.