I just discovered this game. I am very a bad player, so I won't be able to talk about the game itself, which remains me "Evil Donjon" in more beautifull, and different way.
I was completely stunned by the intro screen. Really, the screenshot is beautifull, one of the best I have ever seen in mode 0... on the PC. Yes, on the CPC, the colours are completely different. The colours 5 (basic number) has a really different render.
Here is a picture of the CPC (right clic, "display picture" to see it bigger) :

As you can see, the "5" blue is everywhere.
– the sorceress on the left
– the sorcerer on the right (the blue is lighter that the light on its left side)
– the devil on the right has some blue everywhere on the face
– and some other details.
I guess the illustrator did not have a CPC to draw it. And maybe some small changes are possible without redrawing it, by changing only the palette.
Here is an example :

I only made some small changes :
5>4
2>1
1>0 (eventually)
11>10
10>9
This reduces the palette to 15 colours.
I guess that 14>11 could be good in some parts of the picture only : everywhere but the faces (close to the pink 16) and the beard (close to the light colors). And it could be possible tu keep the palette to 16 colours.
I hope this could keep the spirit/wit of the original illustration.