I watched this movie when I was a kid... and for the life of me I can't remember what it is.

It was about this brother and sister who were playing in an attic and they found this crystal...
And they said something and it took them to this magical place with puppets... one of them was named gus.
He told them how the world was dying because all the crystals were taken by kids like them.
So they decided to go put the crystal back where it belonged...
Not in the attic.

So they went along their quest.
Somewhere they found this giant bubble wand...
Like... as big as them.

So they went to the giant castle and gave it to a giant who thanked them for bringing it back to him.

Blah blah blah somewhow they get to like this cave thing and its all blue inside
And there's this like... pedestal that's a huge circle out of stone.
And there's allthese holes in it.
So the kids put their crystal in one of the holes
And it activates like... a zillion TV screens that show where all the other crystals are...
So they have to go back to the real world and convince these kids to give up their crystals to save the land they came from.

And that's prettymuch all I remember.

All I know is it is NOT "the dark crystal" or "the labyrinth"

"the argon quest" a.k.a. "blizzard island"
It's a feature films for families movie...
So yeah.