Scrap

Nightmare: Clancy starts with 1,000 in the Incinerator Room. Compactors produce more over time (up to 1,000 each; you have to walk over to collect it) and each round pays a bonus for kills and for beating Jack. The third compactor is in the Workshop, behind a door that needs Corrosive.

Nightmare's currency: at the workbench you buy weapons, ammo, traps and upgrades, and the price rises with every purchase. Examples: First Aid Med 100 (+50), Strong First Aid Med 300, Adrenaline 300 (+1,200), Corrosive 1,500 (+1,000), 10 Handgun Ammo 50 (+20), 10 Enhanced Handgun Ammo 150 (+100), G17 Handgun 50, M37 Shotgun 100.

Buy Corrosive early to open the Workshop compactor, then the compactor upgrade.

Many items unlock by points across runs (Adrenaline at 100,000, Enhanced Handgun Ammo at 1,000,000, Strong First Aid Med at 1,500,000). Crafting the Circular Saw or Infinite Ammo multiplies your score by 0.01.