It is unclear how many arenas there are and how they are unlocked. Unless there were 2 from the start I don't know how I got the mining one. (also the Rainbow Blocks don't always destroy the same color.)
Also with everyone else on the progression slowness.
It would be cool if the exchange had an overlay/tab to display the trading functionality from the arena, maybe it costing some upgrade points to unlock so it remains an option.
This game can get addictive. I don't know if the creator intentionally put in some of the common psychological hacks or if they came about organically but it itches an itch for sure.
 "Stacked Idle"){kind=icon}
 "Idle Power"){kind=icon}
 "Moonplinko Kongregate Edition"){kind=icon}
 "KNIVE"){kind=icon}
 "Miner of click"){kind=icon}
 "Dunno"){kind=icon}
 "no-one has to die."){kind=icon}
 "Pheus and Mor"){kind=icon}