The main three secret levels, MAP29, MAP30, and MAP31, can be accessed through hidden exit switches and teleporters in a chronological order not unlike Doom and Doom II, but in a more unique approach rather than getting to the secret levels halfway through the game, the three maps are accessed from stages in different parts of the game (the exit to MAP29 is found in MAP04, MAP30 is entered in MAP12, and MAP31 can be accessed in MAP18). If the level was reached by using IDCLEV or the -warp command line parameter, they will be warped to MAP01.Дoom 64 has three secret levels, one super secret level, and three hidden levels. If the player uses a secret exit on a map they are not supposed to reach a secret level from, they will end up repeating the level over again. Both TNT: Evilution and The Plutonia Experiment, being originally designed as Doom II megawads, follow the same pattern, except that MAP31 in Plutonia does not have a normal exit to MAP16. The first is accessed from MAP15, and the second is a super secret level accessed from MAP31. Another example can be seen in DARKHELL.WAD, where the secret level is accessed from E2M6 upon completing E2M9, the player must play E2M6 over again.Дoom II has two secret levels: MAP31 and MAP32. One example where this behavior occurs is MOUNTAIN.WAD, where the secret exit is placed on E3M5, which results in the player skipping E3M6 upon finishing E3M9, instead going directly to E3M7. Depending on the specific episode and level this occurs on, the player may end up either skipping several maps, repeating the level they just left, or being sent back to an earlier level. However, upon completing the secret level, the player will be taken to the level immediately following the level they were meant to access it from. If the player activates a secret exit on a level they are not meant to reach a secret level from, they will go to the secret level, as usual. They are accessed from E1M3, E2M5, E3M6, and E4M2, respectively. The source port Boom added exits triggered by impact weapons, including secret exits, which are consequently available in any Boom-compatible port.Дoom has four secret levels: E1M9, E2M9, E3M9, and E4M9. In Doom II and Ultimate Doom, secret exits could be triggered by walkover lines as well. In Doom, secret exits could only be set up as switches. A super secret level is a secret level accessed from a previous secret level, as seen in Doom II. Since the secret level uses this second, less accessible exit, the game or episode it forms part of can be completed from start to finish without progressing through the level.

A secret level is an optional level accessed from a generally concealed alternate exit.

Doom lvl 2 secrets