Perfectly chained up snow ball belt of purposefulness is a good idea but I would like it to be indestructible once it loses its 150 missiles and provide a way to refill it back to 150 missiles with either coins or 1-2 donuts. I would hate to see it disappear once used. I have not got to that point yet to see if it goes away.
There should really be set pieces that are a combination of gadget and weapon that are 2 items. Collecting both set pieces would give +7% for 4 separate sets and +5% for another 4 separate sets.
Have all type of stats be represented, IE Brain, Strength, Intuition, Stamina.
This would allow us to customize our builds even more.