Games running on their Real Resolution

I currently set my screen resolution to 1080p.

@FullHornet

Actually thats incorrect, its not the game code that does the upscalling, it's the console itself that does the upscalling that's the way they designed the system it only outputs at 720/1080p, thats also the reason why you cant use the X1 on a 1080i only
screen because it does not support it. this feature cannot be changed by the user at the moment sorry to say OP.

The upscaling is in the game's code so I doubt you can manipulate it unless it came as a result of un update/patch then you could decline that but otherwise it is as is.

Hello "eviltedi"

My Xbox One is also set to 1080p, but there are games that are natively 900p.

Have a nice day or afternoon or night "eviltedi"

thats also the reason why you cant use the X1 on a 1080i only screen because it does not support it.

I, personally, would never want to play games in 1080i. The 'i' stands for interlaced, which I won't get into specifics, but it makes for a less enjoyable viewing experience than progressive scanning.