How can you cheat to have more than the two hardware playfields?

Well, there are more than one way to do this :

One way is to use the blitter to put two of the 'fields' on top
of eachother, ie. two of them use the same playfield. This means
they must use the same colours aswell.

Another technic that is used in many games, is to use the sprites as one
of the playfields. LEANDER, RISKY WOODS and many more use this technic.
The whole secret about this is to use the copper to change the x-position
of the sprites, so that one sprite can be displayed more than once on
each horizontal scan-line. In this way it's possible to have two
'playfields' with 16 colours in each. The problem is that you don't have
the time to change the sprites bitmap-data aswell, so in the playfield
with sprites you must repeat the graphics every 128 pixels in the
x-direction. And if you use more than 4 biplanes, you steal some cycles
from the copper, and then you don't have the time to replace all the
sprites. Here's a copper example of how to replace the sprites :


dc.w	$2C37,$FFFE			; Wait for y = $2c , x = $37
dc.w	$0140,$0040,$0144,$xxxx		; New xpos and data for sprite0
dc.w	$0148,$0048,$014C,$xxxx		; New xpos and data for sprite1
dc.w	$0140,$0050,$0144,$xxxx		; New xpos and data for sprite0
dc.w	$0148,$0058,$014C,$xxxx		; New xpos and data for sprite1
dc.w	$0140,$0060,$0144,$xxxx		; New xpos and data for sprite0
dc.w	$0148,$0068,$014C,$xxxx		; New xpos and data for sprite1
dc.w	$0140,$0070,$0144,$xxxx		; New xpos and data for sprite0
dc.w	$0148,$0078,$014C,$xxxx		; New xpos and data for sprite1

repeat until you reach the end of the screen at x = $D0, and then do this
for each scan-line.

With the above copperlist, you can have a one-bitplane scroller across the 
screen without using any bitplanes, and you still have 6 sprites free!