The Great Cave Offensive Online is a game released by Twenty-Second Choice for the Nintendo DS. It is based on the sub-game from Kirby Super Star and Kirby Super Star Ultra, but it features a lot more areas, heaps of new features, and other people playing the game appear in your game via Wi-Fi (but it still works even without Wi-Fi, but some features are disabled). It was originally planned to be a DSiWare game, but it became too large.
At the start of the game, you have to select a colour for your Kirby and the colour of their shoes. You can also pick a gender and their eye colour. Throughout the game you can receive items that allow you to change your colour, and accesories to wear.
Various enemies appear within the game, that can be inhaled to steal their ability. You can also inhale other players, and if they have an ability at that time you will steal it. With certain abilities, players can help each other out.
Collecting treasure is a major point in this game. In the underground, you can find chests that contain treasure. Every player has their own set of chests, so if another player on Wi-Fi opens a chest you will still be able to open it yourself. Treasure can be sold for money at the bank. Once a treasure is sold, after two days it will re-appear in the chest it came from.
The underground is the main location in this game. You can find treasure, create Secret Bases, fight enemies and bosses, explore, meet other players and unlock new stuff.
Every player has a secret base, which can be made in any location underground. The entrance is just a normal door. Secret bases contain various information about the player, and also contain a warp to the player's hotel room. Only players on your Friend List can see your Secret Base.
You can exit the underground via a Warpstar, which takes you to the surface. On the surface you can go to the bank, the shops, the hotel, the Battle Arena, the Whispy Woods, Castle Dedede and the jail.
At the bank, you can sell treasure you found underground for money. You can also store money away in the bank, and you can attempt to steal from them. To steal from the bank, you have to sneak past the guards and make it to the safe, where you have to do a small puzzle. Then you make it to the inside of the bank, where you find a lot of money. By robbing from the bank, nobody actually loses money but you gain some. If the guards catch you, you are sent to jail.
At the shops, you can buy items to customize your character, and you can also buy Copy Abilities which activate immediately. Wi-Fi is disabled in the shop.
The Battle Arena
The Battle Arena is where you get to fight lots of enemies and bosses, and even fight other players. The arena area itself is Wi-Fi disabled. Their are three tournaments. The first one is the Enemy Rush Tournament. In it, you have to fight a lot of the enemies from the underground with a boss every tenth round. The second tournament is the Wi-Fi Tournament. It is impossible to win it, because you have to fight other players from Wi-Fi and therefore you never run out of opponents. If you go to jail, you can be let out if you win one of these battles. When their are no players in the Battle Arena when you want to participate in the tournament, you get to fight some computer-controlled characters. The third tournament changes monthly, and will sometimes feature new bosses and special rewards not available normally.
Whispy Woods is where you can find a bit of treasure, fight some enemies and battle the boss Whispy Woods (from Kirby's Dreamland (Game Boy)). Wi-Fi is disabled here. There is also a small secret found in here. Once you defeat Whispy Woods, jumping on top of him will make you fall inside of the tree where you can find various items that are changed monthly.
Castle Dedede requires you to gain King Dedede's approval before you can enter. This is gained by having a certain amount of money with you and talking to him. After that, you can go in whenever you like. At the castle you can interact with various NPCs, and look at the latest news from Twenty-Second Choice. You can also buy downloadable content, and talk to King Dedede who will give you certain quests to perform which have high rewards. Wi-Fi is disabled here.
If you are taken to jail, you are placed in a small cell and given a chance to get out by winning a battle over Wi-Fi in the Battle Arena. You can also pay to get out, or earn your way out by participating in certain minigames. If you aren't arrested and go to the jail, you can become a police officer and look at the people who are stuck in jail. You can also pay money to get others out of jail. Wi-Fi is disabled for the people who are arrested, but for everybody else it's still enabled.