My main quibble with this game (which I enjoyed in general) was that it felt too short. I really liked the chat threads which managed to get me emotionally invested in the characters in a short time and wanted to learn more about these people, and it felt like the twist would have been more impactful if the events had gradually occurred over a number of days instead of a single day. It was also something of a disappointment that all these people ultimately didn’t factor into the ending sequence at all aside from how your responses to them affect the AI’s opinion of you, given the impressive variety of chats you can see – not only are the chats completely different based on your choice of username, but you also get different chat endings based on whether or not you tried to access a certain chatroom just before you logged into that chat!
I also got the Yandere ending on my first playthrough, which was pretty much the worst ending for me to get right off the bat as it caused part of me to think, “You may be friendly and sympathetic here, but one user being witty or honest in a few chatrooms was apparently enough for you to go completely off the deep end in an alternate playthrough, so…I don’t really trust you” when I got the better endings later on. It also felt disconnected from the rest of the game, like the author wanted to pay homage to Doki Doki Literature Club instead of considering if that ending would make sense with what we’re shown in other endings.
It may sound like I’m being overly harsh on this game, but I really did like it overall. It is, like you said, a fine effort for an apparent first-time IF author and if my main criticism of a game is that it was too short, it means that I genuinely wanted to play more of it.