Why does this happen if you go out of bounds in older games?

[Gat Pelsinger]

I was wondering that whenever we go out of bounds in modern games, everything renders fine, but in many older games like Doom 3, COD 1, CS 1.6 and more, where if you go out of bounds, your screen starts to glitch out and starts show some repeated frames instead of rendering the void. A similar artifact is shown in the image below.

[Brooksie359]

My assumption would be it's related to how the game was coded/engine being used. I mean engines do things differently from one engine to another and I would assume that older game engines likely worked much differently than modern ones. 

[xAcid9]

Try go out of bound in Motocross Madness.. 

 

[centurion_08]

14 hours ago, xAcid9 said:

Try go out of bound in Motocross Madness.. 

 

Actually non related but how that 980 Ti performs nowadays??

[xAcid9]

19 hours ago, centurion_08 said:

Actually non related but how that 980 Ti performs nowadays??

It's fine. I don't play a lot of new games btw.