Changes and Additions:

1. Player Health Regeneration:
   • Introduced a cooldown for health regeneration, allowing the player to regenerate health after a certain period and after taking damage.
2. Expanded Weapon System:
   • Added new weapons, including a "Knife" and various shooting patterns for each weapon (e.g., "spread" for shotguns, "burst" for certain rifles).
   • Different patterns were implemented, such as "single," "spread," "rapid," "burst," "explosion," and "bounce," each with tailored effects and behaviors.
3. Enhanced Shooting Mechanism:
   • Shooting mechanics were expanded to include features such as burst fire, laser beams, and projectile explosions.
   • Improved bullet creation mechanics, allowing different sizes and damage multipliers based on the weapon characteristics.
4. Health Bars for Zombies:
   • Added health bars for each zombie that display above them, providing visual feedback on zombie health.
5. Save/Load Functionality:
   • Implemented game saving and loading utilizing localStorage to maintain player progress across sessions.
6. Zombies' Behavior Improvement:
   • Ranged zombies retain optimal distances from the player, holding their position and releasing attacks at appropriate ranges.
   • Zombies now attempt to flank the player instead of just rushing in, especially when the player is taking cover.
7. Visual Effects:
   • Added functionality for creating death particles for zombies and tree destruction visuals to enhance immersion.
8. Performance Monitoring:
   • Introduced a performance monitoring mechanism to adjust render culling distance based on frame rate.
9. UI Enhancements:
   • Improved the UI to reflect current weapon states in the shop, indicating equipped weapons, and added buttons for equip actions.
10. Collision Tracking Enhancements:
    • More responsive collision detection with specialized behaviors for knife attacks and other unique weapon types.

Bug Fixes:

1. Collision and Bullet Logic:
   • Improved logic for handling bullet and enemy hit detection to prevent bullets from "sticking" to or passing through zombies and other obstacles incorrectly.
2. Regeneration Logic:
   • Fixed a possible bug where health regeneration might not be adequately reset after taking damage, adding cooldown properties to ensure regeneration operates correctly.
3. Save and Continue Logic:
   • Addresses potential issues that might arise when loading a game if elements were not properly initialized, ensuring that all game state values are correctly loaded without losing functionality.
4. Movement and Speed Adjustments:
   • Refined player movement logic to ensure smoother and more consistent handling of player inputs, especially concerning speed and movement direction.
5. Health Bar Updates:
   • Ensured health bars update correctly when zombies take damage or are destroyed.
6. Memory Management:
   • Added cleanup procedures for particles and health bars to prevent memory leaks when objects are destroyed.