I would call this "Lego for marbles".
A big box, with of separate colourful and robust pieces, which can be put together in endless ways to create sturdy, yet intricate contraptions for rolling marbles.
The marbles roll smoothly, without sticking. They also make some interesting and entertaining noises - banging, clattering, bouncing, whirling. If you build a full and varied run, then release several marbles in quick succession with everything moving at once (wheels turning, lots of noise - bouncing, clattering, whirling), the whole thing can look quite interesting, almost spectacular.
There are no instructions or "suggested patterns" - it's a case of simply opening the box and getting on with it, and to be honest, that isn't really an issue - it's fun to work it out. There is a photo of a completed marble run on the front cover of the box, however I think that is more of a suggestion than a definite promise of what you can build, because some of the "key" pieces in the box were a different colour from the photo.
A few marbles are provided to start you off, and we discovered that the "standard" smaller marbles also work perfectly well.
Finally, as with Lego, it can be broken up and rebuilt at any time - ideal for children with an appetite for destruction.
EDIT: I've added an image: one example of a completed run which uses all pieces provided - see pictures on "main" page for this product.