Heretic keys

This page is about the keys found in Heretic. Although they are more similar to Doom's keys in their behavior than to the Hexen keys, there are a few differences.
 * There is only one type for each key color, as opposed to Doom's system of like-colored key cards and skull keys.
 * The colors are yellow, green and blue instead of yellow, red and blue.
 * Vanilla levels are always designed so that keys are obtained in the order yellow, then green, then blue. This convention is not necessarily respected by mods.
 * On the easiest skill level, keys appear on the automap.
 * Locked doors are drawn with their key color on the automap.
 * Almost all levels are consciously designed to use raise-and-stay-open door types for locked doors. This has a significant positive impact on cooperative multiplayer, ensuring that players who die do not need to pick up every key in the map again to keep playing.

Data
The automap color corresponds to the PLAYPAL palette index used to draw locked doors and, if appropriate, keys themselves in the automap. For convenience, the RGB value for that index in the first palette is also provided.

Appearance statistics
The IWAD contains the following numbers of keys: