Three resources, three jobs
Keys, bombs and coins each open a different part of the game. Running out of one can lock you out of a room or a chest.
The floor gives you a limited supply. Every key you spend is one you cannot spend deeper down.
Keys and locked doors
A key opens locked doors, shops and chests. Golden chests and item rooms may both demand one.
Spending your last key early can strand a better chest later. Ask what the door is hiding before you unlock it.
Bombs do more than damage
Bombs break rocks, kill enemies and open paths. A bomb can reveal a secret room or clear a wall of rocks.
Bombs also open tinted rocks and certain obstacles. Those can drop pickups or reveal hidden routes.
Save one bomb for a bad corner. A bomb in hand is a way out of a room that would otherwise cost health.
Coins and shops
Coins buy items, hearts and pickups at the shop. Prices rise with the item on the shelf.
A shop visit is a choice between health and power. Buying a heart keeps the run alive, while an item raises your output.
Next: Secret rooms guide and Trinkets and consumables.