Bad Heart Mode is an alternate game mode that increases the game's difficulty and caps the player's HP to 3. As such, it is similar to Lunar Shadow's 3-HP Mode and Cave Story's own Hard Mode; to unlock this mode, you have to press Q on the Title Screen.
Unlocking Bad Heart Mode
Obtaining Ending 6 will allow to learn how to unlock this mode. After this, you have to press Q at the title screen to unlock Bad Heart Mode.
This mode allows you to play as Shadow Selena.
A lot of the game's dialogue and messages are altered in this mode, creating a new experience.
The game's secret boss, Andrea Yauman, won't fight you.
The Headmaster and Shadow Maid's true names are revealed.
The three Heart endings replace Solar Shadow 2's normal endings for this mode.
Ending 9 (Bad Heart Ending)
- Aidan Flamberge/Shadow Selena defeats Nought. However, she is not able to become the Castle Master. Terrah then teleports in and kills her. It is obtained by taking the lower path on Bad Heart mode.
Ending 10 (Neutral Heart Ending)
- Shadow Selena leaves the castle. Through willpower, Selena expels Aidan and retakes control of her body. Tirahnys is still invaded by robots, but Selena makes a full recovery and the Tirahnys Intelligence Agency is shut down. It is obtained by traveling to the left from the starting area on Bad Heart mode.
Ending 11 (Good Heart Ending)
- Shadow Selena defeats and kills Terrah, and becomes the castle master. Aidan fully takes control, and announces that he shall have another apocalypse, declaring than all on Newerth shall die in one year. It is obtained by taking the upper path on Bad Heart mode.
Three of Solar Shadow 2's endings can only be obtained during this mode and replace the game's normal endings.
Ending 10 is the easiest ending to obtain since you can just turn left at the very start.
The method to unlock this mode is only explained during Ending 6.
Unlocking Bad Heart mode is rather similar to how FNAFB 2's Q Scenario is unlocked. Co-incidently enough, both modes require you to press the Q button; additionally both modes allow you to play as an antagonist (Shadow Selena and Balloon Boy).
Aidan Flamberge only appears in this mode but doesn't appear during the rest of the game.