There is a show I watched when I was young, It aired on British TV somewhere around late 90s to 2000s. If I remember correctly, it starred a teen boy who fought creatures who came through to this world from another. I can't remember if the other world was a video game or not. I think he had a little sister as well.
I remember a scene took place in a fair where one of these creatures was loose and I halfway remember his sister was in danger at the fair because of the creature.
The show was live action but the creatures were this horrifyingly bad CGI.
As I said I recall very little, but the fair scene with the tiny rollercoaster you only see at fairs stuck with me. I also think there was something to do with electricity in there. It felt like a show was somewhere between Animorphs and Primeval.