A lot of games?
Blockland currently has settings for player shadow's to adjust the quality. GTA IV has settings to adjust shadow quality too. The highest setting makes the shadow's edges sharper, and the lowest settings makes the edges pixelated.
That is a quality setting, it runs faster and looks worse at low quality, runs slower and looks better at high quality.
In other words, you can trade correctness for speed. We will have this setting, it is important for people with slower systems.
However we are not going to support tunable soft shadows (where they run at same speed/quality but the look can be tweaked).