chunky pixel mode

[Mrs Beanbag]

... Because AGA was little more than a bug fix to ECS, and back in the mid 80's bitplanes made sense as you could very carefully control the amount of memory used in your gfx... Once ram became cheap in the 90's bitplanes were a nasty bit of legacy

It also allowed you to do cool stuff like hardware parallax scrolling, easy masking of bobs (in fact it generally makes much more sense with the blitter), really there are a lot of ways in which bitplanes are better for the 2D, sprite-based games you got in the '80s and early '90s, it was only when Doom came out, and then Quake, and everyone got excited about 3D texture mapping that chunky mode became... a game changer.  Suddenly a fast CPU was the most crucial factor, and all the Amiga's clever custom-chip hardware was all for naught.

[Mrs Beanbag]

Chunky mode would have helped, but processing power was more of a bottleneck in my opinion. 030's vs 486's isn't really any reasonable comparison for a CPU intensive game.

This is true, an A1200 with native 68060 would have been truly awesome.  A1600?

[Mrs Beanbag]

if multiple displays could simply be combined together like layers in photoshop, a truecolour display could be made by adding three 8-bit paletted screens together!  (Chunky or otherwise.)  Plus any other weird and wonderful combinations one could dream up...

[Mrs Beanbag]

You could fit a 640x512 truecolour (24 bit) screen in just under 1Mb.  I'd recommend a bit of FAST RAM as well, though.

Put simply, a chunky mode wouldn't use any more RAM than the equivalent planar mode.  Planar modes only save memory if you're not using all 8 bitplanes, except HAM8, which is clever but not much use for games (and in theory you could have a Chunky mode HAM anyway).

[Mrs Beanbag]

The Amiga had virtual spriites. Which could multiple them up to 64 IIRC provided the scan line had enough to work with. The OS even supported them. So you could program the OS instead of trying to work it out yourself.

But there are many complex and difficult limitations for virtual sprites.  Essentially you re-use the same sprites several times by using the copper, so there is no limitation on the number on screen but if you want them to be able to overlap arbitrarily you've got problems.  This trick has been used to get extra layers of parallax.

Also you lose a sprite when you start the screen data fetch early which is required for full screen hardware scrolling.  Note the Turrican game screen is actually 16 pixels in from the left!  Presumably this is so they can use all 8 sprites.

[Mrs Beanbag]

In fact you can re-use a sprite several times on a scanline with clever use of the copper.