Go into hero mode and climb a self-building stairway that literally has no limit to how high it can go.
There are some issues with the 1st 2 or 3 levels, so go slow till u get to 3rd level, and if the stairs mees up in forming, restart the demo. A message box tells you how high a level you are on automatically. If you can't tell which way you are going, use the minimap for reference. Upoper levels are very hard to see.