I'm having a hard time remembering the details, but I think everyone was a YouTuber of some sort. They get summoned to a death game-like setting. The main character is one of those boys who looks innocent but can be cunning...and people start to die. I think there was one of those animal-head guys who was overseeing the death game? Maybe a rabbit guy?

Possibly Doubt (TONOGAI Yoshiki)? Hope it was what you were looking for.

Naka no Hito Genome [Jikkyouchuu]? Though no one dies, really.

Dead Tube ?

Ah yeah I think this was it, thanks! Obviously my memory wasn't great. But the rest of these also look good so I'll check them out...