Assassin's Creed
Now, I'm a big fan of the games, I've played them all to death. I just don't understand how this can have been so badly cocked-up. The cast is great (Michael Fassbender, Marion Cotillard, Jeremy Irons, Brendan Gleeson, Charlotte Rampling, Michael Kenneth Williams...), the budget was big, the material is ready-made for a movie...
It seems to have been put together by people who have just read about the games, never played them.
I'm sure you're already aware, but the games are immersive historical epics with incredible attention to detail and cameos galore - with short present-day sci-fi bits that punctuate the games, the idea being that you're actually playing a simulation in the game itself. So what do they do? Make a movie which is 90% set in the modern world, the one bit that most fans complain about.
Seriously, we were in the past for about 20 minutes of the whole movie. The rest was trudgingly, painfully boring. A wasted opportunity.
It's on Netflix if you struggle with insomnia.