Complete the Land Mode to unlock this game.
Basically the game you play in Land Mode, except this time you go for 999 points.
Get all 100 cards in Normal Land Mode, and complete the game to unlock HARD MODE.
In Hard Land mode, buy the token from the Info Booth in the castle section with all 50 coins and beat the game.
In each zone, for every attraction (besides the Bomber Houses), complete each twice, so you get both the card AND the medal. Once you complete all the attractions for a zone, a new option appears in the Information Centers: SPECIAL. Click that, and pay 10 medals to unlock characters.
Ao-bon (Blue Bomber) - Pay 10 Medals in Spade Zone
Gold Bomber - Pay 10 Medals in Diamond Zone
Kuro-bon - (Black Bomber) Pay 10 Medals in the Castle
Midori-bon - (Green Bomber) Pay 10 Medals in Club Zone
Pretty Bomber - Pay 10 Medals in Heart Zone
Shiro-bon (white Bomber)