How do you open the barred doors in the Binding of Isaac?

Question

These doors are grey and usually (always?) open into a "weapon" room, i.e. there is a weapon on the minimap for them. I've gotten in two, but it was very non-obvious what I did to open the doors. For other doors, I've killed every mob on the floor, put out every fire, and dropped a bomb on the door and it still didn't open. Does anybody know what the rule is for these things?

Answer

The doors are actually tied to your health. The door will only be open, if you have full health. However, the temporary HP boosts (blue hearts) can serve as a equivalent of the missing red hearts.

For example: if you're missing one red heart, and have one blue heart, the door will be open. But, if you're missing two read hearts, and only have one blue heart, the door would still be locked.

Check more discussion of this question.

loading..