Made it all in solo.
You have to predict what will happen and control your bounces a little to allow yourself enough time to catch stuff.

70% seems hard with one player at least.

to access an hidden stage, you have to find a key from the connected level.
You'll find it in the chest that'll appear once you'll collect 70% of the coins of that level.

There's one per world.
Dunno if they drop on easy mode.

I beat the whole game on Easy. How do I get those other levels including the secret one of Bot Vice?

I kept seeing these random keys and didn't understand what they meant. Now I will try to make 100% of the game, thank you!

thanks a lot buddy

It's the final section. Do the rest first.

I regularly get 90% of gems in a level, especially the supposedly connected ones, but still can't unlock the lower right section. If the dots indicating the different stages/levels were organized like an excel sheet (from upper left being A1 to lower right being G9), I am referring to the connection from cell F8 to F7. I've played it dozens of times, each having 90%+, to no avail. Is this a potential bug on my side?

gracias me faltaba un nivel

Thank you very much!