Stipple transparency

This was used back when hardware acceleration of transparent surfaces was still very poor and doing it on software was too slow. In modern games this may be used as a performance boost for transparency that is seen for so brief period that player is unlikely to consider it as worse quality.

Mostly interesting when done on software dynamically, but this can easily be done on the textures/sprites themselves because it's just a specific way of using binary transparency or mimicking binary transparency with alpha channel based transparency.