Boss Attack

Boss Attack is a challenge mode available in the NICALiS ports of Cave Story. It is unlocked once players have completed Story Mode with the "best" ending. The goal of this challenge is to defeat all the bosses without dying in the order of which they are encountered in. Bosses that are optional to face in Story Mode are required in order to progress.

Gameplay

The entirety of Boss Rush takes place in a room that uses the same assets as the Core. At the start of the challenge, the player is equipped with the Polar Star and the 290 Counter is activated. The player then navigates Quote around the room and enters through doors to initiate boss fights. A statue of each boss near each door as well as the preamble text when the player interacts with a door indicates the boss that the player will face against. Boss battles retain the same patterns and phases as they do in Story Mode, but the battles take place in rooms that have a different aesthetic than their actual location in the main game.

If the player successfully defeats a boss, the screen fades back to the main hub, where they can proceed to the next boss fight. A room where a boss has already been defeated cannot be entered within the same playthrough.

Item collection

Experience is found in capsules that are distributed throughout the hub area. Along with experience, Life Capsules can also be obtained in between most boss battles. Most weapons that are obtained can be found in chests, but the mandatory weapons, ie. the Fireball and Blade, are automatically equipped after defeating Igor and Rabid Toroko respectively. A weapon that requires trading in Story Mode can be acquired in Boss Rush by talking to Cthulhu in certain areas.

Boosters

The player is given the option of getting Booster v0.8 before fighting the Core, thus allowing them to use the Booster during the Core battle and not allowing them to obtain the Tow Rope. Once the player defeats Iron Head, they are automatically equipped with Booster v2.0, which replaces the v0.8 if they were carrying it in their inventory. Thus, getting Booster v0.8 does not ultimately affect the player's ability to beat the challenge.

Innacurations

There were some errors during the bossfights that were innacurate to the original fights and could affect the gameplay:

• No tiles in the fans during Balfrog (Fireball bullets, experience crystals and puchis can enter into them).
• Third Balrog fight has his first jump be earlier than normal.
• Curly is taken out by Team 9 robot in fronter tiles at the Core fight
• When defeating Doctor's first phase, it will turn into Muscle Doctor without bouncing the player to the back as normally, which can make the player take damage initially.

Non-stop Boss Rush

There is a hidden unused mode, that still wants the player to defeat all bosses but in a row, and their health will not refill inbetween the fights (only before Heavy Press and Ballos). The initial base plays Running Hell theme and has all the game's weapons but once the player has 6, the remaining chests will disappear. The player will also be able to choose between 55 or 27 health and 27 or 55 missiles, and to level up the weapons, there are three XP capsules with 1000 experience each at the top. There is also Whimsical Star and Mimiga Mask (though the last one doesn't makes the game end at the Undead Core. Finally, the player can also get both Arms Barrier and a single Life Pot.

Once the player has beaten all the bosses, the game says that their time in that mode will not be saved and, if they want to save their time, they should take a screenshot of the screen.

If you wish to access this mode, you have to edit the script of the main Boss Rush area, and acess the event that asks the player if they want to change to Non-stop mode.

Statues

Balrog

Omega

Sisters

Trivia

• At the Non-stop mode, ''Missile'' is spelt as ''Missle''.
• At the WiiWare port, the pool where the player goes to the Iron Head fight has tiles where the player can breathe at the bottom, likely because Nicalis wanted to give fancy fences to it but their tile types weren't water tiles.
• Most of the statues next to the boss doors have innacurations in their drawings, with non-transparent black pixels mostly everywhere.