Simple and straightforward:

I am designing prototypes for video games, that include games that rely on mouse control (strategy, city builders, turn-based) as well as ones that sometimes don’t require mouse control (first-person shooters, third-person shooters). Sometimes a screen does not have a mouse control and is reliant only on keyboard strokes (or gamepad buttons).

This is critical when showing prototypes to users because I need to test whether they can function without a pointer and find their way around a screen where only keystrokes are allowed.

In order to do that I need to be able to turn off mouse pointer on specific screens, but allow them on other. An example would be an FPP shooter, which normally has no pointer on HUD, but reveals one when opening up the equipment screen.