The first one was so awesome, it made it into I Wanna Be the Guy as the theme for the Final Tower of the Guy, continuing on for The Guy's first form!
Breather Boss: King Bee is considered MUCH easier than the previous two bosses and the following boss. He will probably be the only boss in the game where you don't need to use the evolution cheat and can be fought fairly.
Surprisingly when compared to all the other bosses, the Tyrannosaurus are the easiest boss in the game, especially by the time you rematch them as a mammal. They only have 2 attacks, the first is a very telegraphed biting attack (which they often over or undershoot their mark as long as you keep moving), the other is a jumping attack that can easily be dodged; they have no counter to bite-locking, their meat heals you to at least half-health per kill, and the only time the boss theme plays for them is during your first fight with them, every other encounter instead plays the Dinosaur grinding theme.
Broken Aesop: The Survival of the Fittest Aesop gets mangled when the Crystals come into play. After the first era, each era's enemy species use the Crystals to become more powerful and overcome their opposition, so that they can survive in a world of pitiless evolutionary struggle, and they're treated as bad for doing so. Meanwhile, Life uses the crystals as well, and isn't condemned for it.
Demonic Spiders: Many enemies can be this, but the Tyrannosaurus and Allosaurus are the worst of the bunch, being able to cause massive damage very quickly, and also being nearly unbeatable if you're not tall enough.
Cro-Maine. After he tells you his story (that he was bullied by the Monkey-Humans), he suddenly changes from a calm demeanor◊ to being extremely pissed off◊. This forum even mentions that he has emotional issues. How severely did the Monkey-Humans abuse him to leave him so moody?
Boss fights become much easier once the player discovers that undergoing an evolutionary change also has the beneficial side-effect of also healing all your health. Just stock up on EVO points prior to the battle (preferably a few thousand or more depending on the difficult of the boss fight and how expensive it would be to replace a part without hampering your strategy), and when you're getting your ass kicked, just go to your evolution menu and make one small change (like adding a horn), and you'll be back in business.
During Chapter 4, remaining in dinosaur or bird form rather than becoming a mammal becomes this due to how the chapter's earlier stages are balanced around you being a mammal at the very start of their evolution cycle by that point, meaning most enemies are vastly outmatched simply by the fact that your form is balanced for later stages Chapter 3. Thankfully this gets mitigated by the end of the chapter and in early chapter 5, since by that time the enemy encounters will have actually caught up to your own power, and in fact may even be easier if you elected to become a mammal because of the increased versatility.
Goddamned Bats: Trilobites in the Fish Age chapter, most flying enemies if you're not a bird, and the monkeys and dino-people in the final chapter.
It Was His Sled: The Final Boss is a monstrous cell with an awesome battle theme. Thanks to I Wanna Be The Guy, this song is the first thing related to the game some newer players learn.
Most Wonderful Sound: Bolbox makes a very disturbing sound when hit, but when you beat him, he keeps doing it, and it sounds much better as he dissolves to nothing.
Nintendo Hard: This game can be quite challenging. Prepare to grind a lot, or be destroyed by some more aggressive bosses.
The key to boss battles is to go in with a lot of EVO points so you can restore your HP. However, you're bound to run out eventually and die; and your punishment for dying is to lose those very same EVO points. This leads to tons of grinding or forced Save Scumming.
Nightmare Fuel: Bolbox can be this sometimes. The level with the cockroaches borders on it as well. As for the Queen Bee's face... ouch.
Nintendo Hard: This game can be quite challenging. Prepare to grind a lot, or be destroyed by some more aggressive bosses.
The key to boss battles is to go in with a lot of EVO points so you can restore your HP. However, you're bound to run out eventually and die; and your punishment for dying is to lose those very same EVO points. This leads to tons of grinding or forced Save Scumming.
Older Than They Think: The SNES game itself is heavily based on a much older game by Enix called 46 Okunen Monogatari: The Shinka Ron ("4.6 Billion Year Story: The Theory of Evolution"), released only in Japan in 1990 on the PC-98.
Self-Imposed Challenge: Beating the game as a dinosaur, mainly because the Ice Age is slippy-slidey for them, and unlike birds they can't get around that by flying. Also, they're somewhat weaker than mammals, and far less agile.
Sequel Displacement: The game is far better-known than its Japan-only predecessor, 4.6 Billion Year Story: The Theory of Evolution, thanks to being released in English and not requiring a translation to play.
Signature Scene: The final battle with Bolbox. Mainly because of how bizarre the entire scenario is, the awesome music, and the brutal difficulty. In fact, thanks to I Wanna Be the Guy, this might be the first part of the game one learns about.
The Kuraselache Leader is one of the most notable and infamous difficulty spikes in the entire game, being a Wake-Up Call Boss that charges around wildly and can take sizable chunks off of your HP even when fully evolved.
You may have a horrific time with the Queen Bee, even using cheat codes to stay alive.
Despite her Boss Arena Recovery, Mother of Prime Frog is easily the hardest boss in the game besides Bolbox, especially when you're going for a no-evolution-during-boss-fights run. If this were just her, the fight would be a more watered down version of Debustega, but her ability to endlessly give birth to new young makes the fight outright impossible to beat if you don't have either the best armor/attack in the Dinosaur evolution, have loads of at least 1,500 evo points stored up, or even both. You also need foolproof strategy too because if you focus on trying to kill the babies, you'll be left wide open for their mother to slam into you and kill you quickly. Conversely, if you focus on trying to the maximum possible damage to Mom Frog, you'll quickly get overwhelmed and killed by the babies as they softlock you into an unending loop of them hoping over you. You'll quickly learn why she claims "Even Reptiles are scared of us".
Bird-Man King is not afraid to utterly destroy you, being a threat even as the dragon. If you die, you need to do That One Level all over.
Cro-Maine stands outside of the Entrance to Eden, and he can knock you off the stage with his club. He gets his health back from the reset. You, on the other hand, don't.
Mt. Brave is partly this trope and Brutal Bonus Level (it's optional). The Pteranodons living there pick you up and then throw you down to the ground, forcing you to start over. And the reward you get... is becoming a new class of evolutions, forcing you to start over. Unless you figure out how the Cloud Maze and River of Asteroids work, which give you the REAL reward: The Dragon and Gargoyle forms, along with a literal jackpot of Evo Points, allowing you to get back to your most powerful form fairly quickly.
Unintentionally Sympathetic: Bolbox. From what we're told, him getting into Eden would be a disaster, and him being the Final Boss who has previous villains working for him would seem to support this. The problem is that what we do know about him otherwise is rather positive; he protected at least one species in danger of going extinct in exchange for them serving him, which they're happy to do, and the way he recruited his Dragon is a pretty clear Pet the Dog moment. Combined with his surprisingly calm pre-battle monologue, and there's really nothing villainous about Bolbox beyond using the same evolution methods as most of the previous villains, which outright puts him on the same level as the player character.
Unintentionally Unsympathetic: On the flipside, there's the player character. He eats everyone he encounters, mercilessly cheats while getting off scot-free while every other cheater is slaughtered, fat-shames Debustega by laughing at him before killing him, slaughters an entire family of amphibians despite helping their ancestors, does the same thing later with the Yetis (Which at first was justified since Sir Yeti was a Grade-A Jerkass, but even he has a Jerkass Realization upon death while we eat his wife and descendant without remorse), flees through a time-trans while the dinosaurs' world ends, destroyed at least one nonhuman civilization, causing its survivors to devolve into a Woobie Species, and finally proceeds to kill Bolbox, who got to Eden first and saved various species from extinction. Despite all of this, all these actions are played heroically.
The Woobie: Yeti Avenger and Cro-Maine. The former one is the descendant of the Yetis you killed (humiliating the Yeti race in the process), while the latter one was a victim of abuse and bullying by his own kinsmen, the Monkey-Humans, because he had less hair and was smarter than the rest.
For 46 Okunen Monogatari: The Shinkaron/E.V.O.: Theory of Evolution.
Complete Monster: Lucifer in the PC-98 game is far more evil than the villains of the SNES successor. Having tricked numerous civilizations in the solar system into destroying themselves, most recently on the moon, Lucifer now intends to do the same on Earth. She starts at the beginning of life by driving numerous fish insane and destroying the peaceful nature of a small fish village. Later, her attempts to kill everyone become more direct, culminating in singlehandedly causing the extinction of the dinosaurs before gloating to Gaia, the embodiment of the Earth, that she killed everyone. In the last main chapter, after learning that there's still life around, she provokes a war between two colonies of Lunarian survivors by making one of them, Atlantis, obsessed with destroying everything, starting with the rival colony of Mu. This results in the destruction of both colonies. After her defeat and the establishment of human civilization, she gathers power for one last attempt to kill everyone in modern times, resulting in the destruction of the Moon and, consequently, the death of Gaia's sister, before Lucifer is finally killed for good.
Enjoy the Story, Skip the Game: The gameplay was basic even at the time of release in 1990, being a turn-based RPG of one-on-one battles with Level Grinding frequently a necessity for progression. However, the story is more interesting than its successor E.V.O.: Search for Eden, being about a unique blend of evolutionary theory and spirituality along with the heavier focus on interplanetary civilizations.
Esoteric Happy Ending: Inverted with one of the Non Standard Game Overs. You evolve into a wise powerful dragon, Gaia for some reason isn't happy with the evolution path you take, but she gives you an orb and you drive out Lucifer and all her forces, get worshipped as a god and join up with 3 other wise, benevolent creatures to become the 4 guardians. Somehow this is a game over, despite everything being great.
Informed Wrongness: Several of the "bad" endings are defined by this trope, being bad only because the game goes out of its way to inform you that they are; this is most obvious with the Endurance / space-age civilization ending. Others involve Diabolus ex Machina where you found an apparently good outcome only for it to fail because you diverged from the "perfect flow of evolution."
Misaimed Fandom: Some players think that the best ending is the one where the player chooses Endurance after evolving into a human, which leads to the human race enduring and overcoming every struggle and existential crisis thrown their way, through sheer determination, grit, and ingenuity, eventually managing to solve even the problem of global warming, and securing their future, before eventually developing space travel and starting to colonise space and spreading across universe, and consider this superior to the canonical good end from choosing Wisdom, which they denigrate as choosing mystical mumbo-jumbo over actual science. They forget that the Endurance ending has the player wonder whether they made the right decision, wondering whether they diverged from the "main flow of perfect evolution."
Moral Event Horizon: Lucifer firmly crosses it when she has the Great King of Terror wipe out the dinosaurs and proceeds to gloat how she killed everyone.
If she somehow didn't cross it there, then she definitely did by killing and devouring Gaia's sister (the moon) xenomorph-style, resulting in the complete extinction of what was left of the Lunarian civilization before attempting to do the same with the Earth itself.
Scrappy Mechanic: Due to the slippery movement of 46 Okunen Monogatari: The Shinkaron, if your character has a high movement speed one will find some areas tricky to leave due to thin exits that are in the hard to reach centre.
Soundtrack Dissonance: The music for choosing a dead end evolution Non-Standard Game Over is mostly light hearted as though you only made a small oppsie.... even in endings where you die horribly, get enslaved or cause all life on earth to be wiped out
, the regular boss theme
