You need to lock the mouse pointer to one screen. I have a two monitor set up and sometimes when my character is close to the edge of the screen my mouse moves over to second monitor and the game switches to the desktop when i LMB click. I like the game, the graphics and being able to interact with NPCs. Even being able to ally with them (although whether or not they come to help when you need it later idk- would be nice if there was a hotkey for that and they materialize and help fight- but only once. So you need to choose when is the best time).
But i am not a big fan of having to restart from checkpoint if you die and often over and over. What about adding an easy mode (perhaps difficulty level can be changed anytime during the game), where you respawn where you died, or nearest safe point if it was a drop when roping over a chasm for example. But the player will only get half of their BM back or something like that.
Those players who love as it is wont be affected in normal mode and im sure you could add a hard mode for players who have beaten the game. Perhaps also for those who have beaten the game- perhaps they can unlock some new weapons and clothing that they can use on their next new game play through.