Mad Dog and Headdy is the third and final scene of Act 2 of Dynamite Headdy. It is the first real boss fight in the game.
After clearing North Town of Dark Demon's forces, Headdy finds a music hall and decides to explore it. He is immediately faced by Trouble Bruin, who's had his body replaced with a hovering contraption that quickly sprouts menacing-looking appendages. However, before he could challenge him, he is crushed by Mad Dog, the first Keymaster, who faces our pupper hero instead.
Mad Dog has a fairly simple pattern. She joyfully jumps her way forward and swings her tail about, exposing her weak point as Beau will point out. She will then fling herself upwards, and when she comes down her body can crush Headdy, dealing massive damage. A flashing arrow will always appear when and where she's going to fall, allowing players to move Headdy out of the way.
She will have picked up something from her jump that she drops at our puppet hero in hopes of damaging him:
- A green caterpillar who slowly prances back and forth. Has many hit points but otherwise is only harmful to the touch.
- A blue ball containing three dogs on wheels that will jump and run towards Headdy, each faster than the previous one.
- An orange basketball which will bounce off each boundaries of the screen. It will eventally leave the battlefield, but cannot be manually removed and it will have to be avoided.
- Bino, who slowly prances back and forth. Defeating him will yeild the player a Secret Bonus Point.
After a brief period of having dropped what she brought, she will quietly move forward and jump again, land, and repeat her pattern.
Headcase often pops by to help Headdy. Most heads can be of tremendous help for the fight:
- With the Hammer Head, Mag Dog's life will quickly drop, usually being defeated in two or three tail swings.
- With the War Head and the Super Head, the long range will make hitting Mag Dog's tail extremely easy, allowing players to quickly defeat the Keymaster.
- With the Ticker Head, if time is stopped at perfect timing (i.e. Mad Dog's tail is within Headdy's reach), Mad Dog can lose half of her health in one go.
- Players have to watch out though, lest they want to accidentally grab the Melon Head and hope to have enough hit-points to endure the assault until it wears off.
After Mad Dog's defeat, Headdy is left with the Key, but is taken away moments later by a pink Headdy look-alike named Heather, who air-kisses Headdy as thanks, leaving our puppet hero dazed and confused for a second before proceeding with his journey.