As explained in the instructions (You can access the instructions via the "?" button in the main menu in the top-right corner) greed is determined by the added values of your two dice. If you choose to roll again, a need greed will be calculated. If this greed is smaller than that of your previous greed, then you will be overwhelmed by greed, causing you to lose that turn and the points earned in it.
The Kongregate logos spammed on the game's main page make it seem like kong is being forced on someone playing this on another site. Also it looks bad.
 "Chaos Faction 2")
 "A Knight's Story 2")
 "The Final Death Wish")
 "Can Your Pet?"){kind=icon}
 "Greedy Dice")
 "Leekspin Idle")
 "Clockwords: Prelude")
 "Hover Bot Arena 2")
 "Gravitee 2")
 "How to Raise a Dragon")
 "Epic War 3")
 "GemCraft chapter 0"){kind=icon}
 "Remnants of Skystone Beta"){kind=icon}
 "Crush the Castle")
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 "Oroboros")