Sí que inicialmente se rumoreó que iba a tener más colores, así que tampoco ibas tan desencaminado.
Los juegos que superan el límite normal de 64 colores no tengo del todo claro si lo hacen más sobrados en Mega CD o es solo un mito.
While the system was in development, several US video game magazines such as Electronic Gaming Monthly and Gamepro had published reports that the Sega CD was going to be able to display more on-screen colors than the Sega Genesis. It appears that there had been some discussion about upgrading the hardware in the Sega CD to compete with the color capabilities of the Super Nintendo, but it was vetoed.
A common myth surrounding the Mega-CD is in regard to the number of colors it can display on-screen. Like the unexpanded Mega Drive/Genesis, the published specifications of the Sega CD indicate that the system can produce up to 64 colors on-screen out of a global palette of 512 (the same color palette of the Mega Drive). However, many people claim that some games, such as Snatcher, Jurassic Park and Eternal Champions: Challenge From The Dark Side, exceeded the on-screen limit with the use of programming tricks, achieving 112, 192, even 256 colors simultaneously. Some versions of this rumor claim that there was a version of the Cinepak video codec that could render FMV in 256 colors on the Sega CD as well.
The idea of displaying more than 64 colors at once in Sega CD games is not groundless. What is not widely realized, however, is that the Sega CD breaks this limit with the same methods that can be executed on an unexpanded console, and also that these methods are all severely limited in practical use.
The most common way of displaying extra colors is with the use of raster effects, which involve simply changing the on-screen color palette in between TV scanlines as the picture is being drawn. Sonic games use this to make underwater effects. A lesser known trick is to use the priority bit of a pixel for color purposes, allowing any color to have 3 shades (normal, bright and dim) and effectively tripling the number of colors available onscreen. However, this trick compromises the video display processor's capabilities so drastically that it was rarely ever used, especially for in-game graphics. Finally, many developers simply relied on dithering, a simple artist's method of drawing pixels of two similar colors in an alternating, checkerboard-like manner, and relying on the inaccuracy of composite or RF video signals to blend the colors together into a third color. On a side note, this same method could be used to make a fake transparency just by leaving every other pixel blank.
The programming trick which many mistakenly believe can be used to display extra colors on the Sega CD is called HAM, or Hold And Modify. This complicated trick was used with the Commodore Amiga line of computers with the same goal of raising the on-screen color limit. However, the Amiga could also use raster effects, and this is where the confusion most likely started. At some point, it was probably said that a trick similar to one used on the Amiga could be used with the Sega CD to display extra colors on-screen. Since people knew there was a trick to get extra colors out of the Amiga called HAM, they may have then assumed that the Mega-CD could use HAM as well. However, the Sega CD has no support for this or a similar function at all whereas the Amiga's graphic chip was designed for it.