On the morning of December 14, 2000, exactly ten years after the release of the first episode of Commander Keen, the final and single most astonishing event in the history of Commander Keen occurred.

The sky was full of ominous stormclouds, and the thunder that growled in the distance went unnoticed against the pounding of the battering ram that was being bludgeoned against the gargantuan gates of Keen Mansion with the aid of a four wheel drive.

After an hour of battering, one of the gates finally began to give. Using the ram as a wedge, the beseigers of Keen Mansion eventually succeeded in levering one of the gates open a fraction. Just enough for the huge crowd of people to flow through, as the thunder, now louder than ever, rumbled warningly.

But something far more dangerous than thunder lurked within that stronghold.
Until the moment that the gates opened, nobody had managed to set foot in the grounds of Keen Mansion, due to the high voltage security surrounding the mansion's entire domain. The crowd of Keen fans, screaming with delight, ran through the opening and into the enormous front garden of Keen Mansion. But soon, their running slowed. Something was coming towards them. A stampede of creatures that were too distant to be identified. But as the stampede neared the now retreating crowds, the mysterious creatures were still unidentifiable. And then it all became clear what these charging beasts were:

They were Yorps.

Hundreds and hundreds of bipedal, green-skinned, one-eyed yorps flowed across the ground, yipping like dogs. While most of the crowd was retreating, a few people ran ahead to meet the yorps who, in the original episode of Commander Keen, were friendly and, on the whole, harmless. The yorps ripped them to shreds.
Gasps of horror burst from the crowd as they saw humans being flung around in the melee of oncoming yorps. The razor-fanged green monsters tore off these people's limbs, savaging torsoes and heads, while the greater mass of yorps drew ever near.
Those who were inside the gates tried to retreat the way they had come, but the larger crowds outside, oblivious to what was happening on the other side, kept pushing through. Keen fans were crushed by their own people. Some climbed the fence in an escape attempt that ended their lives with a blast of 5000 volts DC.

Guns were drawn. Banners became spears. Pogo sticks became cudgels. Helmets did nothing to save people as the bloodthirsty yorps sank their fangs into soft, unprotected areas, as all the while, lightning hurtled across the wild, rainy skies.

What was to become known as the Mansion Mutants Massacre was the darkest three hours of Commander Keen history, and at the end of it, there was no question: Commander Keen was dead, and Billy Blaze was the one who had killed him.

Among the dead were college student Terence Chalmers, best known for his portrayal of Keen's nemesis Mortimer McMire in episode three of the Vorticons series, and Jakob "Snake" Logan, from the Apogee game Bio Menace.
Chalmers Logan
Both were bitterly ironic deaths, but Logan's perhaps moreso for the fact that the yorps, as was determined after examination, were the product of very advanced genetic engineering; Logan's Apogee character in Bio Menace was that of a man who fought against a mad scientist who created hideous monsters in a genetic engineering lab.

The origins of the genetically engineered yorps is unknown even to this day, but it is suspected that the yorps' genes included those of dogs and bats.

"Well I ain't never seen one o' these critters before so's when I saw 'em all comin' out of the Ol' Keen Place, I was quick to get my shotgun and blast a few o' their green bug-eyes. Vicious little varmints - they was eatin' everyone and there was screamin' and runnin' and people was gettin' crushed in the gate. An' they killed my ol' Grampappy, and cousin Jake, too. We's was fightin' side by side during most o' that battle, me an' Jake, an' then... An' then one o' them devil-critters just jumped him from behinds... and... I shot the thing, but it was too late. Too late... I couldn't save Jake. I just kept fightin' them devil-critters until they's was all dead. But I couldn't save ol' cousin Jake..."

Keenstock was finally over. People seemed more concerned with counting their losses and leaving than staying to try to entice Billy Blaze from his stronghold. No longer seen as a hero, Billy was now held in the public opinion as a madman, an eccentric villain.

Many of the Keenstock attendees, bent on avenging the horrors that Billy had flicted upon them that day, formed a group called "Keen Three". The significance of this name is that episode three of Commander Keen was named "Keen Must Die".

Two nights after the Mansion Mutants Massacre, Keen Three banded together with whatever weapons they could find and set out to invade Keen Mansion itself and destroy Billy Blaze. Men, women and children of all ages and backgrounds marched to Billy's hilltop fortress, brandishing their weapons menacingly.

Encountering no further resistance from yorps or otherwise, Keen Three reached the doors of Keen Mansion and demanded entry. There was no response. The leaders of Keen Three then proceded to douse the doors of Keen Mansion with gasoline and set it alight. As well as this, the battering ram was again employed, and soon the mighty doors crashed inwards. This time, the invaders entered more cautiously than they had at the main gates. Trapped inside his own dwelling, Billy Blaze ran from the hunters like a mouse from a cat.

"It was quite a place he had in there. We all split up into every direction and hunted the insane Commander Keen through his maze. It wasn't long before we found him, holed up in a secret passageway behind one of the walls. It was only because he was carrying his pogo stick that we found him. The metal detector picked up something moving inside the wall, and we soon cornered him and broke open the wall. But instead of killing him, we took him outside, into the grounds where the yorps had attacked."

"There was still evidence of the slaughter that had taken place two days earlier. But what happened next had nothing to do with me."
What happened next was that Billy Blaze was brutally killed by the hysterical masses of angry people who felt betrayed by their hero. As the fists and feet pummelled the life from Billy's body, he made little effort to resist, knowing that there was nothing to be done.
Angry resistance to the murder from some of those present simply agitated the mob further.

Billy's body was propped against his pogo stick onstage like a decaying scarecrow, his form limp and misshapen.

It was the tragic end of an era.