Heya, I'm here for round G of the Secret Santa. Personally, I found the game's idea interesting but clearly the presentation and gameplay suffered from the contest's time limit.
I agree with AubreyTheBard about the tiles and sprites being off-putting, but mostly because I found the bust style to be much higher quality and more interesting in comparison. It's possible that going for a full visual novel style with only drawn backdrops and the busts interacting would've made for a more cohesive look.
Possibly I've read too many mysteries, but I guessed the killer right away and was a bit disappointed that I was right due to a choice the killer made that showed they clearly wanted to be caught (I don't want to spoil it for new players, so I'll be vague), but overall it was an okay ending. The story's grammar and spelling is one of the worst parts of the game unfortunately because of the numbers of errors. I understand that the creator's native language isn't English, but in a story-driven game it's important that everything is written clearly so the player can understand (it took until close to the end of the game for me to realize that the 'reunion' the characters kept talking about wasn't a party but a meeting, which completely changed how I had been looking at interactions). The story could really use a native English-speaking editor to help fix those issues.
The interrogation and investigation modes are a bit rough, but serve their purposes. I didn't find the 'A-F' scoring system to be very useful though, it mostly served to punish the player and since there wasn't a way to raise the score if the player made mistakes early on it could result in game overs repeatedly in the end (unless you do what I did and restart once I knew which options were the right choices). Dropping or adjusting the scoring system could help make the interrogations more fun for the player.
I agree with AubryTheBard about the suggestion of implementing an notes system where the clues could be reviewed, since right now it just relies on the player to remember everything (I ran into a similar issue with my own team's game, so I assume it was more of an issue with the time limit than not wanting to have it in the first place). With more work I think this could be a fun little game, but the contest version currently leaves a lot to be desired.