How about an option for key timing? Like, where when a key is pressed, it gets faded. 5 seconds after the blocks appear it reappears. This would be really useful against key trolls.
I think there should be an option to change the level's natural gravity. Now, I know you're thinking, "That's what the arrows are!" but I'm talking about when, for example, you're in a coin. You automatically go down. With natural gravity changes, you can decide if you would go to the right if you're in a coin. Press + if you agree.
Easy combos:
Lace the bottom with Proxy Mines and Bumpers.
Space Buzzsaws evenly apart at the lowest they can go (add a little space in between) and lace the ceiling with turrets.
Make sure you get the flow level EXTREMELY high!
Brilliant game, I just have one problem... my guys are idiots.
Imagine a square, with an exit somewhere.
They will keep going around and around and around until I get mad, then I stop the raid because they've got no brain cells.