I'm interested in the competitive game modes in Left 4 Dead 2. Can you tell me the main differences between 'Versus' and 'Realism Versus' modes? Specifically, how do their rules and scoring differ, how does 'Realism Versus' make it harder for Survivors, and what are the requirements to play 'Realism Versus'?
Navigate to the 'Gameplay Modes' page on the Left 4 Dead Wiki. Locate and read the section for 'Versus' mode to understand its objectives and scoring in Left 4 Dead 2. Locate and read the section for 'Realism Versus' mode to identify its unique rules, how it differs from 'Versus' for Survivors, its origin, and any specific DLC requirements. Synthesize the gathered information to explain the differences and requirements for both game modes.
State that 'Versus' is a competitive mode where two teams alternate playing as Survivors and Infected, and that in Left 4 Dead 2, Survivors earn points based solely on progression and reaching the safe room. Explain that 'Realism Versus' combines 'Versus' rules with 'Realism' rules, making it harder for Survivors. List specific 'Realism' rules applied in 'Realism Versus': lack of Survivor glows and instant Witch kills. Mention that 'Realism Versus' originated as a 'Mutation' and became a permanent game mode due to community feedback. State that 'The Passing' DLC is required to play 'Realism Versus'.