Why, by using Monique parent the game still runs?

Hello, first about the iron.
Monique - old with a VGA connector
Motherboard socket 1151 ( supports VGA)
Graphics card - GT1030 (supports Dvi-d and HDMI)
Active adapter VGA to HDMI
Now, to the problem. Burned adapter -> can't connect to none. Monique hooked up to the motherboard. Brother, not knowing the history, sat down to play. The game starts and FPS, like if the adapter. Why?