Kill Isaac with Azazel

Construct a furnace out of eight cobblestone blocks.

Harvest some leather.

Construct a better pickaxe.

Craft a workbench with four blocks of wooden planks.

Punch a tree until the block of wood pops out.

Kill Satan

Kill Isaac with Maggy

Kill Isaac with Eden

Beat the Dark Room with Isaac

Unlock any Diamond or Opal Camo

Kill an enemy from behind at close range while disguised by the Sleeper Agent