Yannick

This trick was very common in video games in the 80s/90s, because it essentially gave you some kinds of animation for free. You don't have to waste valuable CPU time redrawing parts of the screen, if you can just tell a few bytes of palette to change and get animation for freepic.twitter.com/aCe8sGyV0M

Waterfalls are one of the most common uses of color cycling, because you can easily make them look decent and interestingpic.twitter.com/O55kT9Rn32

Here's an example where you can see the colors in the palette changing in real time.pic.twitter.com/pZQwpoelxj

Fun fact: Doom (which uses mode 13h, 320x200, with non-square pixels) actually has an effectively double-indirect palette. You've got the game's main palette and a secondary sort of palette called a colormap, which is used for lighting levels.pic.twitter.com/wmfq7Y7ozy

But there are special colormaps, and colormaps that can be overwritten. For example, when you get the Light amplification visor, it switches all sectors to use the colormap 0: full brightness.pic.twitter.com/mxsqO4ZegM

And the original partially-invisible effect was done by drawing those pixels with colormap 6 (normal lighting goes 0-6) This means that in bright background, the monsters shift towards darker colors.pic.twitter.com/moRFJ7Som7

But the most interesting colormap is 32: It's used for when you have the Invulnerability powerup. It is carefully designed so that all colors switch to monochrome, and inverted monochrome at that. That gives the unique effect of this mode.pic.twitter.com/nIDbYW7U4V