Roll 3d10 of all different colors, and the player picks the die they want to use (roll and add or roll under). If the lowest die is good, then you spend its value on good side effects, but if it's bad, then the GM spends its value on bad side effects.

Roll 3d10 of all different colors, and use the two highest as the result (probably roll and add). This concept can be used in numerous ways: I think that's cool, but lacking in crunch, so I'm trying to extrapolate. I have this vague recollection of some horror RPG I glanced at where three dice colors were used, but the only effect was that the narrative should suit the color of die used (it was like hope, madness, or desperation). These good and bad dice essentially color the results (lame pun sorry) in a mechanical way. Regular dice just count towards success, while good and bad dice generate side effects, in addition to counting towards success. I have this idea of rolling dice in multiple different colors: white (regular), black (good), and red (bad).

Green dice table top games