I am getting nostalgic memories about a cartoon/anime that was in the tv when I was a kid, approximately 17 years ago. However lately I was thinking about it a lot and it got my attention, I would love to find out about it.
I only have some some scattered memories so I apologize for that.
They were kids/teenagers and they were using some sort of "hover boards" , which looked like two circles, one for each leg.
They were entering some kind of portals, they were always purple and in the shape of cube. The portals always came down from the sky. There was also "announcer" voice, saying when and where the next portal will be. They called the portals "games". The announcer always said something like "The game is starting in 10, 9, 8..."
In order to enter the "game", they had to stand underneath the falling purple cube. Once it landed, nobody else was able to enter, I think.
I do not remember what was their objective inside or the point of going inside the portals.
Also, they used some kind of flying object , I think it was in the shape of yellowish fish. In order to control it like steer etc. they had to press bunch of buttons in order to do it.