Sonic Jam 6/Art Editing

Title Screen Palette

At ROM:FFFE, there are the four palette lines for the Title screen. The first is the palette line for the big Sonic, the second is for the wings and the circle behind Sonic, the third is for the "Sonic Jam 6" writing and the background, the fourth is unused and contains green and pink repeated for eight times (so it's likely a kind of "free field" for hacking).

0xfffe Sonic palette (Line #1) 0x1001e Wing and circle behind Sonic palette (Palette line #2) 0x1003e "Sonic Jam 6" writing and background palette (Palette line #3) 0x1005e Unused palette (contains green and pink repeated for eight times) (Palette line #4)

Level Palettes

At ROM:16CA, there's the instruction lea (off_EC66).l,a3, which specifies the address where there is the array of pointers to level palettes. Then (usually at 0xEC66) you find an array of pointers. There's a pointer for each level map, and this pointer points to the four palette lines for the level. Once you go to the address specified by level palette pointer, it's very easy to modify the palette. There are four palette lines in standard Megadrive format.