I have a lot of thoughts about this game. (SPOILERS AHEAD)
I understand that this is mostly a metaphor for toxic friend groups and relationships. There are other people in the comments who have explained it a LOT better than I could (Kirby's Explanation is a good source). And there are a LOT of stories where it doubles as horror but also as a commentary... But I think that attempt here, is what makes the game falls flat.
The build-up was AMAZING. Genuinely eerie and sets up this air of mystery that I LOVE !!! Seeing the slow change in June's friends, the mysterious encounters, it was all very exciting. The scene of everyone walking out to see gave me intense chills. I was so ready to see what everything would build up towards, and then - it built up towards nothing.
I've seen other people say the Rachel made this with an open-end on purpose, but imo, this is TOO open ended. It doesn't answer any of the questions it sets up. The only thing it answers is why people were eating metal; to assumedly sink in the water. That's it.
You might be saying, "but it's a commentary! The ending makes perfect sense with what it represents". And that's true! It completes the commentary side of the narrative, but not the actual STORY. It made me feel like everything the GAME's in-universe narrative set up didn't matter at the end. Which really sucks, because I was super invested in the mystery and the characters.
This isn't to say I hate the game! I think it's great, but because it's so good, it makes me sad that the ending falls so flat (for me). It would be super cool to see this expanded on in the future.