If you’ve been following the GIT you might have noticed that MooglyGuy checked in a change to the Midway Zeus driver to improve the blending / transparency effects in Mortal Kombat 4.
Mortal Kombat 4 makes rather heavy using of the blending in places, applying it to a large number of particle effects, projectiles etc.

mk4.zip真人格斗4修复版Mortal Kombat 4 (c) 1997 Midway Games,mame0.165新模拟街机游戏增加特效

The 4th installment of the classic 'Mortal Kombat' series. New graphics, new fighters and a whole new challenge awaits you. Prepare to do battle and take on a whole new dimension.