Mega Missiles are one of the most powerful weapons in Descent, so I believe they need special treatment - which Parallax never really gave them.

One limitation of Mega Missiles was that they had the same very narrow target search cone as simple homing missiles; another one was their limited target acquisition range.

D2X-XL's Mega Missiles will be significantly more aggressive than the original ones. I made sure, however, that this doesn't get out of hand: they will be less aggressive than in v18, where I overdid it a tiny little bit ... (cough).

Mega Missiles also have a slightly different trajectory when they launch from Earthshaker impacts, making a neat turn towards their target instead of flying straight at it right away.

A general change to the target acquisition of all smart missiles is one I found in DXX-Raytracer, where consecutively fired missiles get different targets. In my eyes that makes much more sense than Parallax's solution, where each missile's target was chosen randomly, potentially wasting several rockets or smart blobs on a single, small target. Bosses are treated a little differently though, as they have a higher chance of getting targeted; so if you fire an Earthshaker at a wall near a boss, the majority of all those nice Mega Missiles will hit the boss instead of getting wasted on the minor minions around it.