New Additions:
Integrated Steam Achievement system (as this is a newly added feature, some achievements may not support old save files, and there may still be some bugs).
Clothing vending machine: Ninja.

Difficulty-related optimizations:
Reduced the difficulty of Normal, Hard, and Nightmare modes.
Regular monsters now have a chance to spawn in a weakened state, making them move slower (the chance decreases as difficulty increases).
Challenge stages now have 1 to 3 fewer waves depending on the difficulty level.
Added markers for key doors to the mini-map in Chapter 1.
Reduced the difficulty of the bridge puzzle in Chapter 3.
Increased the critical hit damage of the starting pistol (does not support old save files).
Increased the critical hit damage of the starting shotgun (does not support old save files).
Monsters now take double damage from any source when knocked down.
Improved aim assist for better head locking.

Other optimizations:
Fine-tuned the dismemberment sound effects.
Slightly increased the attack range of the wrench.
Continuously correcting translation errors.

Fixes:
Fixed a bug where the trigger range for the opening cutscene of the Chapter 5 boss fight was too small.
Fixed a bug where the enclosed elevator in Chapter 5 was misplaced after loading.
Fixed incorrect collision detection for destructible obstacle crates.
Fixed incorrect death effect positioning for axe-wielding monsters.
Fixed a bug with the double-dog reward in Chapter 4.
Fixed some clipping issues in certain areas of Chapter 5.