I have been running a game using the d6 Space rules set in a post-war galaxy.
Last night was my first TPK in a LONG time.
The characters were investigating a large Mesa that the natives on the planet thought was haunted by evil spirits.
I thought it was going to be a pretty easy in-between session. A couple of zombies, a few ghouls to fight through and then shutdown and destroy the clone generator that was making them.
With a party consisting of a martial arts master, a biodroid mechanic, human gunslinger and another technician it SHOULD have been a cake walk...especially after I realized that my little 2D clone zombies were not even a close match to the energy-weapon wielding PCs.
I should have known better...
It seems to have started early on in the first cavern the PCs came to, the campfire remains of the last native hunting party were close to a small pool of water. Four tunnels lead from the cavern.
The PCs could hear the 'evil spirits' coming through the tunnels and knew they could jump a long way. Using Transform, 2 of the PCs closed off two of the tunnels, leaving themselves the way they came in and a way to go further into what would end up being an abandoned complex.
Two of the beasts launched themselves at the PCs, one latching onto the biodroid doing no damage but knocking him to the ground, the other tackling the small technician, doing very little damage (bad damage roll, lol)
The gunslinger swings around and blasts the creature on the small technician...oh...look...no more clone-zombie, why? Because I failed to take into consideration that super-heated bolts from a blaster would work like fire...and these zombies took double damage from fire.
The Biodroid, who had readied his hand-held PLASMA torch, sticks it to the torso of the clone-zombie attacking him. Doing enough damage that the clone-zombie runs away back through the tunnel the PCs came out of. As the creature is running away, the martial arts master uses transform to collapse the tunnel, encasing the clone-zombie in stone.
Only one way for the PCs to go now.
So they venture further into the tunnel system, a large thumping sound accompanying the skittering of the clone-zombies movements ahead...and behind...the PCs.
Eventually they get to the facility. They move through standard living quarters that were ransacked long ago, some offices, a motorpool, a hanger and finally find the power-source of the facility.
A large pulsating reactor that is a good 150 or so feet tall, the PCs are standing on a catwalk about halfway down.
Coiled around the bottom of the power-source is a giant snake (the generator is under the floor that the snake is laying on, about 100 feet down, and controls can be accessed from a small office on that floor, of course, the PCs do not know any of this).
The snake stirs when one of the PCs makes a loud noise (not knowing about the snake that the others have just seen).
Okay, so, here is the situation at this point from my perspective:
The PCs have a slightly challenging encounter, the snake will attack and the PCs will have to fight it off without hitting the power core because the shielding around the core is gone, leaking low-level radiation throughout the complex and turning the clones into clone-zombies. The PCs are VERY capable with their weapons, probably a no-contest, but in my head, a decent encounter since the clone-zombies cannot do anything about the PCs (also, due to the clone-zombies not being quite as tough as I expected, the generator has compensated and is now kicking out what amounts to clone-ghouls without any paralyzing touch, just claws and teeth that will actually be able to damage the PCs)
The PCs solution:
Drop 3 fragmentation and 2 concussion grenades on the snake.
Remember what I said about the shielding being down? Remember how the encounter was going to be 'difficult' because the PCs would have to be careful about hitting the power-core? Remember how the only exit they PCs knew about had been blocked off? Not to mention the clone-zombie horde that was now following the PCs...
Three PCs are incinerated in the blast, the fourth actually teleported himself to time-phase shift and avoid the blast...he moved himself about 5 feet or so but he spent 6 seconds outside time-space.
Of course, when he reappears he is 100 feet in the air falling into a steaming radioactive crater. So he uses transform again to give himself wing-flaps, akin to a flying squirrel.
The thermals raise him quickly...he makes a quick stamina roll due to taking damage from the extreme heat...and is incapacitated...the flaps close and he plummets to his death.
And that is how my first TPK in a long time happened.