Difficulty
The game includes two hidden difficulty levels that can unlock due to successful play. Completing the entire game on "Hard" difficulty setting unlocks the more challenging "Chaos" mode. If you successfully complete "Chaos" mode, you'll unlock the ultimate test of skill, "Hell" mode.
Stages
Finishing the game on any difficulty allows you to unlock a stage select option, letting you choose the level you want to play. Finishing the game also unlocks the "Concept Mission" option, which grants access to any concept missions you've downloaded from Xbox Live.
Achievements
"Bullet Witch" features nine standard achievements you can accomplish to earn "GamerScore" points on Xbox Live. Successfully completing each of the six levels earns 10 "GamerScore" points. Clearing the game on "Easy" difficulty wins 50 points. Beating the game on "Normal" difficulty earns 100 points, while completing the game on "Hard" difficulty earns an additional 150 points.
Secret Achievements
Aside from the standard achievements, "Bullet Witch" includes five secret achievements, each worth a specific number of "GamerScore" points. Successfully completing "Chaos" mode wins 250 points. Managing to clear "Hell" difficulty earns you a whopping 1 point. Accumulating at least 15 hours of game play time wins 99 points. Collecting all in-game power-up items earns an additional 150 points, and clearing all stages on any difficulty earns 140 points.
Tri-Serpent
At the end of Level 6, you'll need to defeat the evil Tri-Serpent to defeat the game. Try to remain patient during battle, because beating Tri-Serpent can take 30 minutes or more depending on your upgrades. When the fight begins, Tri-Serpent hides behind a purple shield, making him immune to magic. He'll also attack with devastating fireballs, destructive foot stomps, pillars of fire and a snake arm that renders instant death. Stay at a safe distance and attack with midrange weapons, focusing on his shield first. Once you destroy the shield, unleash magic attacks on his snake arm. You'll also need to defeat Grudge Spirits the entire time, which helps you recharge your magic. If you get behind Tri-Serpent, shoot him in the spine with your machine gun, as his back is his most vulnerable spot. Keep pressing the attack until he slows, staggers and falls.