Each PC starts with a pool of several d6s and 50 hit points. The setting is a tall tower, treacherous mountain range, or any obstacle that must be climbed to overcome. On you turn, describe a hazard (creature, trap, rockslide, etc.) and how you overcome it. Roll a d6, take that amount of damage, then place the d6 in the center of the table. After each new hazard/die roll, the player stacks their new die on top of the previous one in a growing tower representing Uncertain Doom. Whoever causes the tower to eventually fall over counts all the face-up pips and takes that much damage. If their hit points are 0 or less, that player has died. If they're still alive, they may continue climbing. (Gather all fallen d6s aside for the endgame.) When all but one PC lies dead, the survivor must now escape by climbing back down by stacking *all* previously fallen dice in the center of the table (without rolling anew). If the tower falls, they take that much damage. If they still live, they may continue until they escape their hazardous journey or until the Heights claims its last victim.
This mini-RPG could represent any “climbing to get there” challenge: approaching the deadly wizard in his tower lair, a group of SWAT members climbing up a skyscraper under siege, a plucky team of hobbits returning a certain ring to the top of Mount Doom, etc. Most will die during the journey, but will the last survivor escape to tell the tale?