@ptoing: Ok, it depends... Still to lazy to check it out if ECM would look better.

Maybe I should keep the multicolor mode.
@pypeBros: You could see the lifts as part of an egyptian machinery, well... ok. I think I would prefer moving blocks instead of moving plattforms. The longer top-plattform is nice. Like this the shadow looks ok. Haven't started on drawing traps, yet. I am so slow in pixeling.
"Embrace the limits, don't fight them" - that sounds like a sentence from Spock...

Unfortunately, I am still fighting against them in this post. On my notebook, I can zoom the graphics to 3x. (On other computers even more) These are very big pixels and dithering looks odd somehow. To come around this, I made a little converter to display the graphics in a C64 emulator. Maybe the game should have some CRT-monitor emulation? (or am I getting crazy now?)

Here's a part of the 3rd mockup in reverse mode, using the C64 emulator "vice" with enabled CRT emulation. (On the bottom are Helm's pixel clusters)
- I have spotted 2 things in the CRT emulation: a) dark scanlines, b) blurs the colors to the next pixel
- dithering looks better (?)
- seems like I can mix some colors on the C64? (I made some tests on the right side)
blue and brown / yellow and light green - do these colors mix to a new color or what? Should I use these effects? I have the feeling, at least the C64 game "mayhem in monsterland" does color mixing this way. It's hard to say, because I could only find screenshots without monitor-emulation. But the stripes in the screenshots are very omnious.

Here's a test with single blue hires pixel (top half) and wide pixels (bottom half).
- single pixels have less brightness (?)
If someone wants to check it out on a C64:
compare1.prg compare2.prg
Some test rocks... In reverse mode, I can use 4 colors for the rocks, but then I cannot use blue background like in the picture above and I would have to use 3 colors. Except I utilize the color mixing from above for a 4th color. What do you think?