The first round started on Titan and the champions were fully automatous. Humanity's champion landed with retrorockets that flamed white, igniting the oily sludge the covered the icy surface. Methane rained down on its flanks as it settle and waited five hundred years for its foe.
The other champion was for a long dead species that has spread to sixteen systems in the direction of Virgo before it died out, consumed by a fitter civilization that hadn't yet touched any of Earth's descendants. The champion of dead species (unaware of the fact), landed a mile from humanity's champion, and the latter, detecting the landing, came to life inside. The surface engines revved up, and claws scooped up material from the surface for the reactors to feast on.
The dead species champion lased a hole into the surface--sludge poured in, greasing the sides, burning and charring, and the champion began to burrow towards Titan's layer of molten water magma. Humanity's champion unfurled wings, and briefly ignited its rockets to gain altitude, and glided towards the enemy. The dead species champion, sensing movement, crawled up out of the hole and aimed it's lasers at the wings of humanity's champion.
The great machine pitched and rolled in the murky sky, then fell, spiralling, thrusting out various sets of legs, impacted the ice, sending shards spinning up into the atmosphere. It scrambled, scratching for purchase on the ice--the enemy lasers burned out again, blazing and arcing, criss-crossing rapidly, and where the endpoints touched the ground, the hydrocarbon sludge flamed up green and blue.
Humanity's champion rolled and ducked behind an ice outcrop--the reactors revved up to maximum and threw out a concentrated magnetic pulse in the direction of the enemy. The dead species champion was momentarily stunned, and while it rebooted it's systems it fell and stumbled back into the whole. Humanity's champion leapt up over the outcrop and dashed for the hole, which was too small for it to pass into. It stomped on the sides of the hole, crushing ice and sending in large boulders, burying the enemy champion. It spun up it's array of magnetrons and flooded the hole with microwaves, melting the ice to slush, then watched it rapidly refreeze and solidify, entombing the enemy.
But the enemy was not destroyed. Its internal systems recycled, and then it continued its burn down to the magma, where it released its payload: the micro-organisms of its home planet, for a fresh start at evolution.
Yup, 'magma' on Titan is actually just liquid water (ask ESA/NASA). Also, apparently, the gravity is so weak and the atmosphere so thick (1.5 times that of Earth's) that humans could fly by merely flapping strapped on wings--which is mindblowingly awesome, although you'd probably freeze to death in a matter of minutes (the atmosphere isn't toxic, but you'd need supplementary oxygen and a really warm parka).