Since the current supermagnet skill sort of breaks the game later, in a bad way. I would propose that after a certain point, it disables the magnet completely and just autocollects everything at the bottom. Maybe by making the white snow at the bottom the same color as the mouses's. If one would then disable the magnet you could make it so that if you do collect it with the mouse you get a larger bonus. Perhaps the previous one squared.
I think it would bee cool with some more unique upgrades and such instead of the milestones. Maybe add an upgrades section with one-time upgrades that gives upgrades that are a bit more unique.
@Gazthomas for Tangerine Tycoon i think that it would be nice if the world population would have a difference. Now it's just a number that does nothing at all. Maybe sparing the world population would be a long term choice while quickly killing it would give you some tangerines quickly. I'm sure something like that would be fun.
another way to force you to use different elements is if each element's spells would be different in some major way, maybe how they charge up or something.
i think there's an easy solution to forcing you to pick different elements, making it so that, essence elements are distrubuted to the ones you DON'T use, and if you you many, they're spread more evenely. I think that would make me not only use dark spells.
 "Ultimate Assassin 3"){kind=icon}
 "Poker Quest RPG"){kind=icon}
 "Synergism"){kind=icon}
 "Yet another Merge Game"){kind=icon}
 "witchy sacrifices"){kind=icon}
 "Simple Mult Idle"){kind=icon}
 "Idle RPG"){kind=icon}
 "Idle Snowflakes"){kind=icon}
 "Antimatter Dimensions"){kind=icon}
 "Idle Mage Attack"){kind=icon}
 "Computer Clicker"){kind=icon}
 "Idle Bouncer"){kind=icon}
 "Tangerine Tycoon"){kind=icon}
 "Spell idle 2"){kind=icon}
 "Aisleen"){kind=icon}
lets see, you can already get that far and further