Persistent Difficulty (PvP)
Low difficulty human civs receive a bonus production yield (+10% per difficulty level up to +30% at settler). High difficulty human civs receive a nerf to production (-10% per difficulty level down to -40% at deity).
Removes the extra starting units that AI civs receive on hard difficulties. High difficulty AI civs only receive bonus yields to production, food, and gold (+25% per difficulty level up to +100% at deity). Removes bonuses to combat strength and combat xp for both AIs and players.
