ExoTerra

From BoardGameGeek:

Welcome to the universe of ExoTerra, a sandbox strategy game with tactical planning, deep customization, and enemies who are complex and highly challenging. ExoTerra is played cooperatively over the course of many sorties in a campaign. Each Player takes on the role of a Pilot in charge of requisitioning equipment, personnel, supplies, and, most importantly, Jackets – massive humanoid weapon systems, to be customized and fielded in battle. Leveraging a new system of enemy generation, battles should always feel different, even if facing the same enemies. This is accomplished through several factors of enemy customization that force players to assess each situation individually. You can rely on your experience from past battles, but must be able to change your strategy on the fly based on the variables of the mission. -description from the designer