Because the game is large (often exceeding 40GB–50GB), it is frequently split into smaller "RAR" volumes for easier downloading. To use this, you would need all preceding parts (1 through 4) and any subsequent parts in the same folder to extract the full installer.
This indicates a specific update milestone. Version 1.1.328 was a significant patch that addressed various stability issues and compatibility fixes following the game's "Legend of the Kestrel Lancers" expansion era. MechWarrior.5.Mercenaries.v1.1.328-GOG.part5.rar
MechWarrior 5: Mercenaries puts you in the cockpit of a massive BattleMech in the year 3015. You lead a company of mercenaries across the Inner Sphere, balancing repair costs and salvage rights against the chaos of interstellar war. Because the game is large (often exceeding 40GB–50GB),