EarthSiege is played from a first-person cockpit perspective. The main objective is to complete combat missions by destroying designated enemy units, protecting allied forces, or reaching required locations while keeping the HERC operational.

Before and during missions, the player manages weapons, ammunition, power, armor, and damage. The campaign is divided into missions, with successful operations advancing the war and providing access to different HERC configurations and equipment. Careful positioning, target prioritization, and heat and ammunition management are more important than continuous firing.

Study the mission objectives before engaging. Use terrain and range to control encounters, and avoid exposing the HERC to several enemy units at once.

Conserve specialized ammunition for durable or dangerous targets. Monitor armor and system damage, retreat when necessary, and tailor the machine’s equipment to the expected opposition.