First of make sure you have a reference object.

    Start by creating a cube. Make sure it has a decent length, at least three times its’ width. Also, the height should be high enough so the player can walk up the stairs. Not too shor though, remember, this will be spiraled and the shorter the stair is the less ceiling room you will get.

    Duplicate this cube using the Radial Clone tool using a degree measure of 20. This is only for reference when creating the stairs and will be deleted later.

    With the first cube selected cut across making it into a triangle. The cut should be exactly where the 2nd cube’s front is. Delete the 2nd cube and the peace under the 2nd cube.

    Use the radial clone to create another copy, still with 20 degrees.

    Using the knife tool cut across the end of the first peace. If you are following these directions and pictures exactly the first point should be at the bottom left corner the second should be anywhere that will make the line touch (not intersect) the bottom left corner of the 2nd peace. You may need to change the grid spacing in order to do this.

    Delete the 2nd peace. Now you can use the spiral clone to create how ever many stairs you need. The settings should be 20 degrees with (in the case of this tutorial, if any deviations were made settings may vary) an offset of 0.25 on the Z axis.