First of: Cool to see a new remake. Well done so far!
I had a look at the original and there's no rainbow bars, and the font appears to be too small in the remake. (See attached screenshot. Added also, so others can get an impression how the original looks like without having to install an emulator.)
Who can help me to do it ? (scroller Coloreffect)
A cheap way for the color effect of the static text (that's how I'd do it
) would be to create an image with the color effect and let it cycle behind the text where white is set to transparent.
Same goes for the scroller. Create a box or something behind it and let it change it's color with use of a random timer. I don't know how this was done on the C64, but hey you coded it didn't you?
For the bars: Draw a line and let it change it's color with a timer.
I'm sure there are better ways to do it. But maybe this helps for a start.
Hang in there dude, I'm curious about the 100% version