Originally posted by Biscuit:

Note: All of this is pertained around the One Against Many, Two Against Many, Hardcore Common Problems and Common Problems mutations from Rayman1103's Mutations on Expert difficulty. Please play on those modes for the intended experience.

• Finales are now shorter. (Only applies to official campaigns.)
  
• Props and other objects are now randomly added to official campaigns. Can potentially alter map routes, such as a fence blocking the street in No Mercy's first level.
  
• Survivors have decreased movement speed.
  
• Actions such as healing, hanging from a ledge, helping a Survivor up from a ledge and map actions (i.e. turning on the generator in Crash Course) are now in first-person and have no cinematic lighting.
  
• Survivors die upon reaching 0 health instead of incapping.
  
• Ammo piles have a high chance to be replaced by Tier 1 weapons, with the exception of ammo piles in finale areas.
  
• Ammo piles can only be used once before depleting.
  
• Tier 2 weapons have a chance to be replaced by Tier 1 weapons.
  
• All weapons, including fully loaded weapons, are now one pick-up only.
  
• Breakable wooden boxes now have a chance to drop items upon destruction alongside various props.
  
• More item spawns have been added.

• Common Infected now walk and shamble slowly towards players rather than sprint.
  
• Increased Common Infected spawn rate and capacity.
  
• Common Infected's HP are increased to 250 from 50. (Headshots can still take infected down in one hit.
  
• Uncommon Infected and certain types of Common Infected (i.e. police officers, nurses) can drop additional supplies such as pistols, pills and more.
  
• Common Infected are now alerted to players' locations after firing a gun. Certain guns have a larger detection range than others.
  
• Special Infected no longer spawn.

• All primary weapons have reduced ammo reserves.
  
• Pistols and Deagles now have their own ammo reserves and can be depleted.
  
• All guns have a clicking sound cue when reaching low ammo.
  
• Melee weapons will now break after extended use.

• Pipe Bomb has been converted into a grenade. No longer beeps and will explode much sooner.
  
• Molotov fire spreads farther and lasts longer.

• Pain Pills and Adrenaline now take a short period of time for their temporary health to build up, rather than instantly gaining the temporary health.
  
• Adrenaline lasts longer and gives more temporary health and movement speed.