Extreme Battle is a minigame that was introduced in the Dual Shock edition of Resident Evil 2, and later implemented in the Dreamcast, PC and GameCube ports of the game; despite coming out around the same time, the Nintendo 64 version of RE2 does not include this mode. It is unlocked on the consoles by completing Scenarios A and B on Normal (expecting that the player meets specific timing requirements), and saving the clear file when prompted. It is available upon installation on the PC.
Like its predecessor, Battle Game, Extreme Battle tasks the player with surviving a long gauntlet of enemies while using a limited supply of ammunition and health supplies.
The chosen character starts in the Underground Umbrella Lab and must race up to the Raccoon City Police Department, obtaining four Anti-virus Bombs found in the R.P.D. precinct. Then the bombs are planted around the Umbrella Train to eliminate the zombie threat on the surface.
The Anti Virus Bombs are scattered around specific R.P.D. areas (found only in these locations). A bomb found in a certain place in one game may not appear again in the same area in the next game.
Despite the bomb-finding objective, the players can also search the Underground Lab, Sewage Disposal Plant and R.P.D. for ammunition, healing items, weapons, and possible weapon upgrade parts. The mini-game features the ability to save using Typewriters, just like in the main game. The amount of Ink Ribbons given varies per level.
There are three levels of difficulty, with new ones being unlocked by completing the previous ones. Items become more scarce and stronger enemies more common in higher difficulties.
Level 1 :
- The easiest difficulty. Locations are filled with lots of ammunition. Damage dealt by enemies is minimal. The Anti Virus Bombs are almost found always in the same areas. The player is given 5 Ink Ribbons to save with.
Level 2 :
- The middle difficulty. Locations contain less ammunition than Level 1. Damage dealt by enemies is moderate. The bomb locations are now slightly randomized. The player is given 3 Ink Ribbons.
Level 3 :
- The hardest difficulty. Ammunition is scarcer than the two previous levels. Damage dealt by enemies is very high (it often takes only 3 hits from enemy attacks to kill the player at full health).
- At this point the dog-like Fourth G-Mutation of William Birkin will roam around at certain areas (he is a very dangerous enemy).
- The bomb locations are very much randomized at this level.
- The player is given only 1 Ink Ribbon.
Players must search for four Anti-Virus Bombs in the f.f. R.P.D. areas: (take note that the locations are randomized depending on the difficulty)
- S.T.A.R.S. office
- Holding Cell
- Operation Room
- Night-duty room
- Cog Room
- Press Room
- Taxidermy Display Room
- R.P.D. Back Lot (the place where the player first enters the R.P.D. station in Scenario B)
- Licker (Mutated)
In the beginning only Leon and Claire are available. Ada is unlocked after finishing Level 1, and Chris is unlocked after finishing Level 2. Each character sports a different armament, but otherwise plays the same.
Leon Scott Kennedy
It is possible to pick up additional weapons or weapon parts in specific areas:
- Submachine Gun: found in the Power Room of the Underground Laboratory
- Rocket Launcher: found in the Sewers
- Handgun Parts (for Leon): found in Sleeping Quarters in Lab B4F
- Shotgun Parts (for Leon): found in the Sewers
- Magnum Parts (for Leon): found in the R.P.D. Evidence Room
Players are graded based on the amount of time they take to complete the game. The best time and character used in a specific difficulty is recorded. Players are encouraged to beat either the preset records or their own.
- Chris' damage grunts are recycled from the first Resident Evil.
- Chris displays idle animations when not moving for some time: He will go into a "thinking pose" when armed with his handgun, and when equipped with his shotgun he will tap it impatiently over his shoulder just like in the first Resident Evil.
- The Herbs were misspelled in the PlayStation version, calling them "Harbs". This was fixed in the later ports.
- Finishing Level 3 will depict a morning picture of Raccoon City, while the epilogue is being typed on screen.