The tricks used to get more than 16 colours on the screen are are limited in their use.
The main problem is that you end up with 16 colours per scan line and sprites or "graphics" do not mormally want to change colour as they move around the screen. In all you end up with 16 colours on the screen.
Cockpits for example would be one of the few places this method could be used.
Other methods such as "HAM" type stuff which means each pixel can be its own colours run into massive CPU overheads, this can not be used for most games, especially not 3D stuff.
