Summary:

1. Added the "Hero Level" system, where players can accumulate experience points by using heroes in battle. Increasing hero level can earn Gacha Coins! More exciting content is coming soon!
   
2. Added different recoil to bullets, while reducing the recoil of weapons. Different combinations of bullets and weapons will produce more distinct recoil.

Levels:

1. Added the "Castle" level, unlocked after clearing the "Grass" level.
   
2. Significantly reduced the health of all enemies in all levels, lowering the difficulty of the game.

Heroes:

1. Added the "Vampire" hero, which can be obtained through Gacha or by clearing the "Castle" level. The vampire carries dual pistols as its initial weapon, and its hero skill is "Blood Bullet". When the energy is full, it can increase the upper limit of the heart count by 1 point and can consume 1 heart at any time to give its bullets a bloody appearance, significantly increasing damage.
   
2. Fixed the issue with the Knight's display when using two-handed weapons.

Weapons:

1. Added the "Buffer Gun", which does not generate recoil.
   
2. Added the "Riot Shield", which can block enemy projectiles.
   
3. Optimized the shooting sound effects of the robot's mechanical arm in red mode.
4. Reduced the movement speed reduction of the Gatling gun and heavy machine gun.

Bullets:

1. Added the "Bat Bullet", which has a chance to drop a heart when hitting an enemy.
   
2. Added the "Ghost Bullet", which has a chance to not consume bullets when fired.
   
3. The shooting speed reduction of the Sprite Ball is no longer a fixed value but is determined by the weapon's firing speed.

Cards:

1. The Demon Sword has added a spiral movement trajectory.

Other issue fixes:

1. Fixed the problem where the player character would continuously receive projectile damage without being invincible.
2. Fixed the issue with the perspective angle of weapons and enemy projectiles.
3. Optimized the sprite images of weapons, bullets, and some heroes.