The lack of snap coloring in osu!mania leads to situations in which certain maps become infinitely harder to time. Maps such as Fullerene-'s Dreamless Wanderer, or Valedict's Badboy that were already tricky to time on Etterna, even with the assistance of snap coloring. So these maps become barely readable on osu!mania. Since most of the ranked/loved maps have the notes snapped to some divisor, it would make logical sense for the player to be able to see such a quantization during gameplay and not just in the editor.
To implement snap coloring in osu!mania, you basically need to store different colors of each circle for each quantization. Here's an example, and it's what Etterna or FFR does:
1/1 note - red
1/2 note - blue
1/3 note - purple
1/4 note - yellow
1/6 note - pink
1/8 note - orange
1/12 note - cyan
1/16 note - green
any other quantization/unsnapped quantization - gray
For a given column, you would have .png's for a red circle, blue circle, purple circle, and so on. Or you could have a .png of all the colored circles in a row.
This would help immensely to some players and would be very cool to see this getting into the game, and would provide more options and tools to players to customize their aesthetics to what they think it's perfect for them to perform
