After an unknown apocalyptic event wipes out all life on Earth, demonic monsters leave the underworld hoping to take the planet for themselves. However, they encounter unexpected resistance in the form of an army of aliens from a far off planet who have come to claim Earth as a new colony world. The aliens give the monsters an ultimatum: submit or be eradicated. The monsters immediately decide they are having none of this and prepare to take the fight to the aliens. It's then that 108 stone slabs erupt from the earth. Written on them are cryptic messages about humanity's extinction and hints that the truth can be found at the mysterious Tower of No Return.
The monsters assemble a group representing each demonic race - Orc, Harpy, Skeleton, Giant Snake, Gargoyle, Goblin, Cyclops, Slime, Golem, Dragonewt, Minotaur, and Androsphinx. The 12 set off to battle the alien invaders to decide the successor to Earth and to discover the truth behind humanity's destruction.
The game has never been translated or released outside Japan. Brain Grey's dissolution prevented any direct sequels from being made, but developer Pandora Box led by the game's writer later made a Spiritual Successor named After Armageddon Gaiden.
Last Armageddon contains examples of:
- After the End: The game starts after all of human civilization was destroyed in an apocalyptic event.
- Alien Invasion: The main antagonists are an army of aliens invading the now desolate Earth to turn it into another colony for them.
- Beneath the Earth: Upon reaching the top of the Tower of No Return it's revealed that what the monsters thought was the surface of the Earth was actually a massive underground cave. The Tower of No Return acts as a sort of elevator to move between the underground and the true surface.
- Blob Monster: The Slime party member, a living pile of green slime. He learns poison and acid-based abilities, and his race is described as having been born from humanity's pollution.
- Blocking Stops All Damage: Using the Defend Command prevents a monster from taking damage for the turn.
- Cool Versus Awesome: One of the main premises of the game is classical monsters fighting aliens.
- Cyclops: The Cyclops party member. He appears to be a deformed humanoid with a single eye who fights using clubs. His later evolutions become even more monstrous but always keep the single eye.
- Dem Bones: One of your party members, just called Skeleton, is exactly that. He's one of the few monsters that can equip most weapons by default and as an undead, he can't be poisoned.
- Draconic Humanoid: Dragonewt, who appears to be a humanoid dragon. He specialized in fire magic and can sprout wings to fly around the world map. His later evolutions lose humanoid shape and he becomes a pure dragon.
- Evil Versus Evil: The conflict between monsters and aliens could be described as this in the first half of the game. The aliens are genocidal tyrants, but the monsters don't exactly have any morals to speak of and are fighting just because the aliens are muscling in on their turf.
- Evolution Power-Up: A major gimmick to the game is that your monster party members evolve and change forms as they level up. Their first three evolutions are linear progressions into natural extensions of their base forms. For their fourth and fifth evolutions, the monster takes DNA from another party member of your choice, giving them the inherent traits and abilities of the monster they took DNA from. You can choose between three options for their fourth evolution and two options for their fifth, giving each monster six different potential final forms.
- Fake Memories: Upon reaching the top of the Tower of No Return, the monsters learn that they were created by humans and that all their stories of having fought with humans in the far past and memories of living in the underworld for hundreds of years are fake. It was all implanted in them by the humans so they would act out their role as demons.
- Golem: The Golem party member, a humanoid made of stone. As he's already made of stone, he can't be petrified.
- Harping on About Harpies: Harpy, who appears as a woman with eagle wings and feathered legs. Fittingly, she learns special attacks involving her voice and spells that charm enemies. Her evolutions become more bestial, with her second and third ones turning her into a gryphon and pheonix.
- Humanity Ensues: The ending has the demonic monster protagonists transformed into humans to repopulate a restored Earth.
- Humanity's Wake: All of humanity was wiped out some time before the game starts, leaving the demons as the planet's inhabitants.
- Infinity +1 Sword: The Azoth Sword. It's the only weapon to be gotten through an event instead of crafting, and it has way higher attack power than any other weapon. In earlier versions of the game you could potentially get a copy for every party member. The PC Engine version balanced it more by letting only the Orc and Goblin use it.
- Item Crafting: The game has no shops, so all items and equipment are crafted by your party. Unlike most versions of this trope, you don't need to collect and use certain items to make what you want, instead, you expend Jin that you get from defeating enemies to make the items.
- Lack of Empathy: It's stated that the monsters are lacking in emotions, especially ones like compassion. It's implied that the reason humanity was destroyed was that they lost contact with many of their emotions and destroyed themselves as a result. The monsters were made as representations of humanity's inner demons. The monsters' main goal for much of the game's second half is exploring the ruins of human civilization, finding objects that spark emotions within them and cause them to gain the emotions of love and kindness.
- LEGO Genetics: The monsters are able to inject other monsters' DNA into themselves, which causes them to evolve into stronger forms that carry the gameplay traits and abilities of the monster they took DNA from. These fused forms tend to look very strange, sometimes nothing like either of the original monsters, although there are patterns like forms with Skeleton's DNA usually having skull faces.
- Living is More Than Surviving: The idea is touched upon in the recordings in the Tower of No Return. The records on the age of dinosaurs say that humans discovered a way to read the memories of dinosaurs through their fossils. From it they found out that the dinosaurs wished to die because they were sick of their monotonous lives, and were grateful for the Ice Age wiping them out. The recordings imply that such a feeling of emptiness is an inevitable part of evolution, and was a factor in humanity destroying itself.
- Monster Adventurers: Your entire party consists of various monsters, who can evolve into even stronger and freakier monsters.
- Our Gargoyles Rock: The party member Gargoyle, who appears as a demonic-looked winged humanoid. The gargoyles' statue origin is touched on when Gargoyle see an old statue of a gargoyle when exploring the ruined surface, which sparks thoughts within him about how what is considered an evil monster can change dramatically with the change of human values change.
- Our Goblins Are Different: One party member is a Goblin, who looks like a short imp-like humanoid. He's one of the few party members who can equip most weapons.
- Our Minotaurs Are Different: One is your party members is a Minotaur. He appears to be a large, muscular man with a bull's head and legs. Fitting the usual image of minotaurs, he specializes in using axes.
- Our Orcs Are Different: The party member Orc, whose race looks like humans with blue pig heads. He's one of the few party members who can equip most weapons.
- Our Sphinxes Are Different: Androsphinx. In her default form she's the least monstrous looking of any of the party, appearing to just be a human woman with headwear similar to that of the Egyptian sphinx. As she evolves she becomes less human-like, first growing wings, then turning into a manticore and chimera.
- Perspective Flip: At one point in the game your team of monsters will have to fight enemies that appear to be human Fantasy Character Classes which are actually robots.
- Robotic Reveal: After the party kills a group of enemy human Fantasy Character Classes in the fantasy land, the "humans" are revealed to be robots. The human "king" is also no exception.
- Snake People: Giant Snake, who looks like a large red snake with a human-like torso and arms. He learns poison-based magic and is immune to being poisoned. He becomes more bestial as he evolves, turning into a hydra.
- Starfish Aliens: Most of the alien enemies you fight across the game are extremely bizarre, sometimes to the point of being hard to interpret what it is you're even looking at.
- Stat Grinding: Instead of gaining EXP from killing enemies and leveling up the traditional way, your party members gain individual EXP for each stat by taking actions related to that stat (attacking physically to raise strength, using spells to raise magic, etc.). Enough EXP increases that stat's "level". Your monsters do have overall character levels as well, but they're determined by the overall EXP they have among all their stats, and its only direct effect is your monster attaining new evolutions at certain character levels.
- Surprisingly Sudden Death: The starting cinematic of the game has a Skeleton and Minotaur minding their business and talking to each other with nary a foe in sight, when out of nowhere a laser shoots the skeleton in the head and shatters its skull. Almost immediately after, the minotaur gets turned into Ludicrous Gibs, and then only are we shown the killer.
- Tomato in the Mirror: About halfway into the game, the monsters reach the top of the Tower of No Return and learn that they're not the monsters of ancient myth that they believed they were but were actually created by humans before they went extinct. They were created as representations of humanity's sins and vices, and are implored by messages left behind to learn from humanity's mistakes so that they won't repeat them and destroy themselves as humanity did.