The spiral stairs on Dust2 are no strangers to my videos. I attacked them in my ‘New Dust2’ one the other day for having the same dodgy clipping as the older map did, and also covered them in length the other year as part of my sprawling epic stair clipping video which I suggest everybody checks out as soon as possible. To recap, they clipped the top and bottom stairs, allowing for smooth navigation, but left the middle ones bare, causing one’s vision to viciously vibrate as one ascends or descends the said stairs. No doubt they had tried to clip them, but quickly ran into a limitation with Source. The engine CS:GO is based on really doesn’t like the shape made by trying to smoothly clip the area between stairs. You can do it in the editor, but it won’t work in-game and reloading the map will reset the clips to different, inadequate shapes. Source requires each side of a shape to be flat, and a ramp that goes around corners like this curves one of the faces in some grotesque way. Using 2 clips per stair instead of 1 avoids this problem and although the result isn’t a perfect ramp, it’s certainly smoother than no clipping at all. Problem is, if the step is narrow enough then it results in a ramp that’s steeper than 45 degrees.

It’s at this point that a ramp becomes a slope that’s steep enough to stop players from running up. This is what happened to the inner edge of the spiral staircase on Dust2. Approach it too close to this side and you’ll come to a dead stop, only able to move backwards or sideways to shallower ground. Indeed, Valve attempted this method but chose not to use it because of this trade-off. This 45 degree angle isn’t a problem with stairs. So long as stairs are no taller than 18 units each, you can have them as narrow as you like. Which itself leads to some weird situations that wouldn’t work in reality where players can ascend entire floors almost instantly.