1991年4月26日，Kemco發行獨立的Game Boy動作益智遊戲《米老鼠2》(ミッキーマウスII /Mickey Mouse II)，卡帶的記憶體容量為1M，可以通過密碼來進行續關。因為Capcom當年擁有在NES上開發迪士尼遊戲的授權。因此，這款美國版本被命名為《兔寶寶:瘋狂城堡2》(The Bugs Bunny Crazy Castle 2)。這個系列與紅白機(Famicom)版本不同，整體難度更高。

故事情節講述米奇要解救被角王綁架的米妮。需要通過29個關卡並打敗最後的頭目來拯救女朋友。

雖然沒有時間限制，但敵人會快速追趕。必須收集8把散落的鑰匙才能打開通往下一關的門。碰到敵人會立即死亡，收集起司可以增加一條生命。拿到武器後可以攻擊敵人，最終的頭目需要被箭射中三次才能擊敗。除了第一關和最後頭目的舞台外，其他舞台都可以通過輸入密碼到達。

畫面右下角顯示鑰匙和箭的數量。站在“UP”地板上就會向上漂浮並跳到較高位置，“W”地板是進行傳送。當持有箭或炸彈時，按下“A”可以投擲。移動到門外並按上鍵可以進入房間。榔頭可以用來敲碎石頭，而投擲箭或炸彈可以立即消滅敵人。一旦進入門後，它就會保持開啟狀態，不需要重新進入，但可重複進入來躲避敵人。通過每個關卡後，密碼就會顯示在屏幕右下角，接關沒有次數限制。

所有28個關卡的密碼如下：2: TEST 3: GAME 4: SHIP 5: RACE 6: WORD 7: SHOP 8: SIZE 9: QUIZ 10: DOLL 11: DATE 12: ZOOM 13: DISK 14: GOLD 15: ZERO 16: FIRE 17: ROOT 18: READ 19: TAPE 20: UNIT 21: SONG 22: TYRE 23: LOVE 24: NOTE 25: JAZZ 26: HELP 27: KING 28: GIFT

On April 26, 1991, Kemco released the standalone Game Boy action puzzle game "Mickey Mouse II" (ミッキーマウスII / Mickey Mouse II), with a cartridge memory capacity of 1M and the ability to continue levels using passwords. Due to Capcom's authorization to develop Disney games on the NES at the time, the US version of this game was named "The Bugs Bunny Crazy Castle 2". This series differs from the Famicom version and is overall more challenging.

The storyline revolves around Mickey's quest to rescue Minnie, who has been kidnapped by the Horned King. To save his girlfriend, Mickey must navigate through 29 levels and defeat the final bosses.

While there is no time limit, enemies will quickly pursue Mickey. To progress to the next level, players must collect eight scattered keys to unlock the door. Coming into contact with enemies results in immediate death, but collecting cheese adds an extra life. Armed with weapons, Mickey can attack enemies, with the final bosses requiring three arrow hits to defeat. Apart from the first and final boss stages, other stages can be accessed by inputting passwords.

The bottom right corner of the screen displays the number of keys and arrows. Standing on "UP" platforms allows Mickey to float upwards and reach higher positions, while "W" platforms serve as teleporters. Pressing "A" when holding arrows or bombs allows Mickey to throw them. Standing at doors and pressing up allows entry into rooms. Hammers can be used to break rocks, while throwing arrows or bombs instantly eliminates enemies. Once a door is entered, it remains open, although players can re-enter to evade enemies. After completing each level, a password is displayed in the bottom right corner, with no limit on the number of continues.

Here are the passwords for all 28 levels: 2: TEST 3: GAME 4: SHIP 5: RACE 6: WORD 7: SHOP 8: SIZE 9: QUIZ 10: DOLL 11: DATE 12: ZOOM 13: DISK 14: GOLD 15: ZERO 16: FIRE 17: ROOT 18: READ 19: TAPE 20: UNIT 21: SONG 22: TYRE 23: LOVE 24: NOTE 25: JAZZ 26: HELP 27: KING 28: GIFT