Zombie Panic! Source, a beloved Half-Life mod unreleased for 20+ years, finally hit Steam. Its appeal centers on asymmetric multiplayer design: humans manage limited weapon inventory capacity (overloading slows movement) while facing durable zombies, creating resource-scarcity tension. A signature panic mechanic lets survivors dump items for a temporary speed boost to escape, generating high-risk/high-reward decisions. The gameplay excels when both sides' mechanics stay balanced, delivering engaging asymmetrical tension.