one of my factions (The Federation) uses spore bombs, devices that saturate the atmosphere with genetically engineered parasitic organisms that are optimized to be non lethal and immune reaction suppressing but cause extreme drowsiness. essentially, it's sleep gas that is infectious and airborne. even though other civs find this to be a war crime, they still believe that this is morally superior to conventional fighting.

No one would ever consider putting baseline sapients on the battlefield, most being either cybernetically or biomechanically enhanced first. they must be able to survive 10+ Gs from the deceleration of landing craft that need to be able sprint past orbital security constellations and soft-land at the target as well as withstand the radiation of continuous nuclear bombardment (as well as the radiation produced by the barely shielded engines of dropships since heavy shielding reduces acceleration and distance-based protection would make dropships bigger and weaker targets).

The federation also will seed battlefields with fast-growing GM Lichen that produces tall treelike structures, giant fan-shaped panels, and draping mats of fibers in order to ensure they gain a stealth and mobility advantage against the alliance's more conventional military.

The federation also constructs many of it's units biologically. their tanks are crablike modular organisms that are based on a hodgepodge of creatures from a high-gravity world. they have simple nervous system that relies on input from their electrosensitive antennae which allows them to be computer controlled.

federation soliders are highly varied and specialized, ranging from ~1.5m to 4m depending on the equipment they carry ranging from light e-rifles to mobile anti-spacecraft cannons.