Sherlock Season 4 Finale: 13 Dumbest Moments From 'The Final Problem'
5. The Game Relies On Sherlock Breaking The Rules
Almost the entirety of Sherlock's time at Sherrinford plays like a sequel to Saw rather than an episode of Sherlock, with Eurus in the role of Jigsaw. She pushes them into increasingly dangerous games, pitting them against each other and forcing them to kill.
It all culminates in a scene where Sherlock is forced to choose between killing Mycroft or Watson. This itself leads to one pretty good moment (Mycroft's 'performance'), and one daft one (Watson agreeing he should be the one to die, forgetting he has a daughter already without a mother).
But the crux is, what if Sherlock really had gone through with it? If he'd shot one of them, then the entire endpoint of Eurus game wouldn't have worked. It required him breaking the rules. Which, sure, maybe she knew that's exactly what he'd do. Or maybe the writers just don't have a clue what they're doing anymore.