Another account of a lifeform from the game in action against mankind...
In the deep of night, First Platoon Sergeant Nolan swept his camp perimeter with his multiscan imager. Radar had picked up motion out in the dark yet thermal showed nothing. Sweeps for EM also were showing zilch. Switching to low-light revealed nothing but the windswept rock plain, patchy grass and scattered boulders.
There was no way any sort of mass movement was going on out there--there just wasn't enough cover. Checking his perimeter seismic logs for activity showed there were a few scattered impacts at the time of the radar hit. It had to be falling rocks--there wasn't any other credible explanation.
As Nolan was putting the imager down and reaching for his coffee, the radar op shouted out, "Major motion! 230 degrees, 1600 yards!". Leaving the coffee, the sergeant snatched up his imager and swept the coordinate. The hair on the back of his neck stood up because this time he heard the rumbling--nothing made that much noise except ground armor, yet, the sound wasn't quite right.
Thermal and EM scans were still blank so once more he shifted to low-light and patched in the perimeter seismic detectors. Sure enough, the ground sensors were showing a large, moving blob heading directly for his position. He tuned in the optics and for the first time saw the enemy they had been searching for all this past week.
The enemy was rocks...and lots of them.
Yard wide boulders and smaller, roundish rocks rolled toward camp in a large herd. It wasn't an avalanche because there was little slope--in fact--they were moving up slope.
Nolan blinked...looked again...and then ordered the 40mm Oerlikon quad to open up on the boulders. "That will show what's hiding in them." he thought to himself--though damned if he knew how they were making those boulders roll.
The silence was shattered by the long explosion of the quad firing and Nolan cursed as the flash from the first burst zapped his imager--it would take a few minutes for low light viewing to be restored. With the light of the muzzle flashes, Sergeant Nolan could see shattered stone shards exploding from the dust cloud. There were no cries, no "spang" of armor ricochets and no secondary explosions.
Frustrated, he screamed out, "Cease fire! Cease fire!". Luckily the gunner was quick to respond and the smoking guns fell silent. Everyone in the camp was up and armed now--weapons at the ready and trained on the target. Slowly the dust blew away and revealed--a lot of blown up rocks.
In disbelief, Nolan stepped down from his stand and advanced towards the shards of stone scattered about the crater the quad had dug. Multiple spotlights illuminated the area now and shouting, "Cover me!" he sprinted forward--determined to catch any hostiles trying to crawl away. They had gone many a sleepless night and damned if he was going to let a couple of harassers come in and then crawl out unharmed.
He reached the area and there was still nothing. No snares or traps were in evidence--and they couldn't have survived the pounding of those Oerlikons at point blank range anyway. There were also no bodies...no body parts...and no blood trails--nor any pieces of scrap from blown up enemy drones.
The sergeant picked up one of the smooth round stones lying at his feet. It was just a stone. As he pondered what that meant, the last thing that passed through his mind was the very stone he had just held in his hand. He never heard the screams of his men as boulders the size of vehicles dropped from the sky directly overhead onto their camp.
The next morning, a recon team sent out by headquarters found the slaughtered unit--buried under tons of rock in the middle of a flat, open plain.