[Coco] Thexder RGB vs Composite Mode.

[Robert Gault]

OK, the "bug" if you want to call it that is a table of equivalent color values 
stored in the ROM at $C1F7-$C216. The first half are the RGB colors and the 
second half the CMP.
Since the CMP colors are not correct, I'd bet that they were taken from a 
reference without testing. The only way to correct the problem would be to burn 
a new EPROM with a better color equivalency table.

Creating a better table is easy but time consuming. You need to use MESS which 
can flip at will between CMP and RGB colors. Write a program that changes 
palette colors on command and try to match CMP and RGB colors.
Specifically for each RGB entry in the Thexder color table, find a matching CMP 
color. With a revised color table, you could play the game in MESS with a 
patched ROM image if you can't burn an EPROM.

You should be aware that you can't match perfectly CMP and RGB colors. However 
you ought to be able to get closer than those used in Thexder.