Introduction is the starting area of Quake. This level is a hub level, made only to link to other levels. It's an experimental concept which allows the player to select the Episode and Difficulty through in-game navigation, rather than the traditional splash screen.
In this hub, the player selects a difficulty and level by going through corridors to the area they wish. The Easy selection is a clean and simple hallway, the Normal selection is a more menacing metallic bridge over muddy water, and the Hard selection is a broken bridge over a pool of Lava.
The Episode entrances are designed to reflect the nature of the dimension they lead into. The entrance to the Shareware episode, Dimension of the Doomed, is a simple idBase-themed room. A dark and sinister Wizard-themed hallway leads into The Realm of Black Magic. A bizarre walkway over Lava, bearing the distinguishable characteristics of the Runic style, leads towards The Netherworld. An eerie room, an example of Elder World architecture holds the slipgate to The Elder World. Finally, a hidden final passage leads deep below the hub, into Shub-Niggurath's Pit where the game's final battle takes place. Overall this level does not have a specific Level Theme, as many different textures are used in an attempt to show the capabilities of the engine, which means that this level has parts of all themes which is stored in a separate .wad file.
The player will return to this room to select another episode after they beat an Episode. The entrances to completed Episodes will be sealed off and will not available for playing until a New Game is started. Weapons and Ammo do not carry over to this level, meaning the only new item a player will have after each Episode is a Rune.
Quick Level Completion
- Choose your difficulty (If this is the first time you are on the map).
- Choose the episode you wish to play.
- When all four episodes are done, go down the stairs to the exit to the final level.
Select your Difficulty via walking through one of three corridors into a Teleporter at the end, marked from left to right - Easy (for rookies), Medium (For beginners and trainers), and Hard (For experienced players). The three different levels change the number and type of enemies encountered. On the Hard passageway there is a Lava pit to jump over.
Once you chose your difficulty, you must choose the episode you wish to play. From left to right the Slipgates are Dimension of the Doomed, The Realm of Black Magic, The Netherworld, and The Elder World. Once all four episodes are completed, a new passageway will open in the ground leading to Shub-Niggurath's Pit, where Shub-Niggurath awaits you.
Nightmare (the hardest Difficulty, hidden to avoid being accidentally chosen by inexperienced players) is found by going down the passageway of The Elder World until arriving at a pool of Water. Dive in the pool, but keep to the side you jumped off of. Sliding against that edge, keep going until you fall onto a pair of wooden beams. Walk across the wooden beams over to another passageway leading to a Teleporter that has a red fluid in the middle instead of brown. Shoot the Button nearby to get a message telling you that the Well of Wishes awaits you in the Crypt of Decay. When you cross through that you will find the entrance to Nightmare Mode. Nightmare uses the same monsters as Hard, but makes them move and fire faster.
- Entering the Teleporter to Shub-Niggurath's Pit "from below" will send you to the console since this particular Teleporter lacks a corresponding exit.
- 25 Health in Easy corridor
- 25 Health in Normal corridor
- 15 Health, Nailgun, and Nails in Hard corridor
- Shells to left of Slipgate to Episode 1, and a Double-Barrelled Shotgun to the right
- Grenade Launcher in corridor to Episode 2
- Rockets to left of Slipgate to Episode 2, and Yellow Armor to the right
- Rocket Launcher in corridor to Episode 3
- 2 Rockets, 2 Cells, and a Thunderbolt at Slipgate to Episode 3
- Red Armor at back of Water to Episode 4
- Super Nailgun at Slipgate to Episode 4
- Nails in middle of room of Episode 4
- Nightmare Teleporter leads to Teleporter to Shub-Niggurath's Pit
- A Teleporter leading back to Episode 4 corridor, Cells and Rockets to right of Teleporter to Shub-Niggurath's Pit, and a Quad Damage to the left
- Nails, Shells, and 100 Health on stairs to Shub-Niggurath's Pit
- Right of the starting pad
- In the Easy corridor
- By the Episode 1 Slipgate
- In the Episode 2 corridor
- In the Episode 3 corridor
- In the Episode 4 corridor
- According to John Carmack, id Software received a money offer from an "early Internet company" to insert a sponsored advertisement in this level, but id Software decided not to on basis of it being ‘tacky’. 
- For the corridors leading to each Episode, John Romero emulated the various level design styles for each of the designers. He tried to keep the lighting and brushes identical to the style of the individual level designers, making it appear like it was something the designer would have naturally created. 
- The entrance to Episode 4: The Elder World features a pool of shallow suspended Water where the player will (unless they try to swim up) drop straight through to the bottom floor which will injure them (unless the player slides along the edge that they you jumped off of, where by falling upon a pair of wooden beams they can either go for Nightmare difficulty or reduce the drop height for the floor to Episode 4 such that no health is lost). This was intentionally designed to be unfair, since the player who jumps into the pool would have no idea that a steep drop awaited that would injure them. This was done by John Romero as he felt Sandy Petersen loved to make crazy ideas that made little sense, but were at the same time interesting. Romero also felt that Petersen enjoyed making sadistic traps that were relatively unfair to the player, saying "Here's your torture!". Sandy Petersen himself did something similar in E4M2: The Tower of Despair. 
- The difficulty selection room appears as a hidden secret area in id's 2011 first-person shooter RAGE. Referred to there as the "Quake Room", it can be accessed from the Wasted Garage area by activating three hard-to-see switches, which opens a panel in a wall revealing a Quake-style portal leading to the Quake Room. The room features exactly the same low-res textures as the original one, and while the selection portals are non-functional, the lava under the broken bridge to the Hard difficulty is still lethal to the touch. A collectible Shambler plushie can be found in the area as a memento for the player.
- post by John Carmack where he stated, ‘We had a pretty good money offer to put a sponsored add [sic] in the Quake 1 entry level. We decided not to just on the basis of it being tacky, which was for the best, considering the company (some random early internet company) disapeared [sic] into obscurity.’
|N/A||Quake Levels||E1M1: the Slipgate Complex
E2M1: the Installation
E3M1: Termination Central
E4M1: the Sewage System