The 'altitude range' slider in the design map parameters wizard determines the steepness of your map.
This is demonstrated below, where where I've made terrain with altitude range settings from 0% up to 100%:
Altitude range | Design map | Heightfield | 3D render |
---|---|---|---|
0% (left, flat) | |||
25% | |||
50% (centre, default) | |||
75% | |||
100% (right, steep) |
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