Jagex - Whatever happened to this?

Just to cut into the speculation here: We did try this. Had it working in game. But it was less fun than the version without moving terrain. And whilst it does sound cool, and is an idea I'd like to revisit for future, our goal for the Colosseum was to make a difficult, fun piece of content. We tried this, it wasn't making it more fun, so we cut it!

I did worry that we'd already mentioned them on stream but we can't let our old ideas hold the game's fun hostage. Fun comes first!