They mean, that they used bricks of Lego(c) to build a playing environment. It's in the nature of those bricks, that anything can be built with them.
If I have understood Jos and Sico correctly, when they told me about the early days, characters also had to pay for bricks they wanted to use for a house, or for a car, or for whatever they intended to build. The intriguing feature, which has not been mentioned yet, was that those bricks became very scarce eventually (just because Jos and Sico ran out of them

), making them an incredibly valuable resource.
I might have misunderstood this point, though. But to me, this (using lego bricks as a universal building material that characters had to pay) was the most intriguing aspect. Which I have probably made up, due to misunderstanding. But still...
