Sell Max is unlocked when you equip the Chest artifact. Ingot purity currently does nothing.
i love this game and i am enjoying what ive played so far but i do have one question why is this not on steam ? its far from good enough to be there even at a cost of a dollar or two even at the stage the game is in now (maybe release it as early access?) i would definately buy it and im sure some of my friends will too