Opening Stage

Opening Stage (オープニングステージ) is an introductory stage in the Mega Man series that is played before the stage select screen with the (usually eight) bosses. Opening Stages were introduced in the first Mega Man X game.

Mega Man 7
The Opening Stage is a city that is being attacked by Dr. Wily's Robot Masters, who free him from prison. Mega Man tries to stop Wily, but he faces Mad Grinder and Bass.

Enemies:
 * Metall SV
 * Bunby Tank
 * Boss: Mad Grinder
 * Boss: Bass

Mega Man 8
The Opening Stage is in a skull-shaped island that was used by Dr. Wily as a hideout. When Duo and an evil robot crash on the island, Dr. Light asks Mega Man to investigate.

Enemies:
 * Aloha Dodonpa
 * Ammoner
 * Bunby Tank DX
 * Metall SV
 * Boss: Yadokargo

Mega Man & Bass
The Opening Stage is a robot museum infiltrated by King. King cuts Proto Man in half and uses the Green Devil to cover his escape.

Enemies:
 * Changkey R
 * Dodonpa Cannon
 * Fire Metall
 * Joe Classic
 * Metall SV
 * Monopellern
 * Mole
 * Boss: Green Devil

Mega Man Powered Up
The opening stage, named Towntown Stage (タウンタウンステージ) in the saved game data of both English and Japanese versions, is the town where Dr. Light's Laboratory is located. Dr. Wily steals Dr. Light's robots and sends Proto Eye after the player to cover his escape.

Enemies:
 * Beak
 * Octopus Battery
 * Spine
 * Boss: Proto Eye

Mega Man X
The Highway Stage (ハイウェイステージ), named Central Highway in Mega Man Maverick Hunter X, is a highway from Abel City that is attacked by Mavericks in the beginning of the game. X faces Vile in this stage.

Enemies (X Mode):
 * Bee Blader
 * Ball De Voux
 * Bomb Been
 * Crusher
 * Gun Volt
 * Jamminger
 * Road Attackers
 * Spiky
 * Boss: Vile

Enemies (Vile Mode):
 * Bee Blader
 * Ball De Voux
 * Crusher
 * Dig Labour
 * Road Attackers
 * Rush Roader
 * Boss: X

Mega Man X2
The Maverick Factory Stage (イレギュラー工場ステージ) is a factory used by Mavericks. X fights the Gigantic Mechaniloid CF-0 in the factory.

Mega Man X3
The Opening Stage is in the Hunter Base. In one point X is captured by Mac, and the player must use Zero to save him. After freeing him, Zero leaves and X fights Maoh the Giant.

Mega Man X4
Sky Lagoon Stage. Eregion. Magma Dragoon. Colonel.

Mega Man X5
The Opening Stage is in a city with a giant statue. The Sigma Head comes out of the statue to attack the Maverick Hunters.

Mega Man X6
The Opening Stage is inside some ruins with Mavericks. After defeating D-1000, Zero Nightmare appears to destroy it, and later High Max appears.

Mega Man X7
The Opening Stage has two parts. In the first half Axl is escaping from Red Alert, and the second has Zero fighting against Mavericks in a highway. In the end, the two work together to take down Mega Scorpio.

Enemies:
 * Bee Blader
 * Guard Door
 * Ball De Voux (both Normal and Shot Type)
 * Guard Fan
 * Kyuun B
 * Radarroid
 * Runnerbomb
 * Surveillance Radar
 * Boss: Mega Scorpio

Mega Man X8
The opening stage is Noah's Park, an area near the Jakob Orbital Elevator in Point Galapagos.

Enemies:
 * Batton Bone S
 * Bombee
 * Bulbrite
 * Bustard
 * Crabs-K
 * Float Gunner
 * Guard Generator
 * Land Torpedo
 * Met
 * Moledig
 * Protectoral
 * Queen Bombee
 * Spiky
 * Boss: Crabs-Y

Mega Man Xtreme
The Opening Stage is a reproduction of the Highway Stage from Mega Man X.

Mega Man Xtreme 2
The Opening Stage splits in two parts at one point. X takes the top path, while Zero goes by the lower path.

Other
Mega Man for DOS features something like an Opening Stage, with Mega Man walking along a straight path to enter what seems to be a part of Dr. Wily's Castle, the only enemy appearing being a dog-like robot vaguely resembling Velguarder which respawns indefinitely. The stage ends when Mega Man passes through a boss-room-esque door. This can be considered the first Opening stage in a Mega Man game.