"Far away on a planet similar to earth, a new life form emerges- a life form that ingests other creatures, absorbs their DNA, and then somehow is able to assume the characteristics of their prey. These greedy, merciless creatures are without conscience. The are the most purely evil and dangerous of all known life forms. What fate awaits these amoral predators, which soon will come to be known simply as... EATERS!"
Chimera Beast takes place on a planet which is described as distant and Earth-like. The planet is overrun by animals known as eaters, capable of eating other creatures and acquiring their abilities or characteristics. The player controls one of these eaters and progresses through the game by means of evolution, consuming microscopic organisms in the first stage, fish in the second, and so on. When the player's creature gets big enough to take on humanity, the goal of the game is revealed. The planet's humans have developed space travel, which the player must thwart, so as not to give the eaters a means of escaping the planet. There are two possible endings: one in which the player is able to stop the eaters from escaping the planet, and one in which the eaters do escape and, we are told, will eventually make their way to Earth.
The chief innovation of Chimera Beast is its power-up system. Instead of collecting gun upgrades as in most games of this genre, the player's eater enhances itself by eating other creatures and assuming their abilities and defenses. Instead of simply having various types of projectile weaponry, the game attempts to make these new abilities as varied as possible. Consuming a crustacean might give the player's eater a hard protective shell, for example, while an insectoid creature might offer a poisonous tail instead. The game even includes the ability to use cancer as a weapon.
Another difference from typical shooter mechanics is that the player's eater does not die after being hit. It has a life bar, which can be charged by consuming enemies. It is even possible to eat enough charge the life bar past its starting position, creating a larger eater which is not only more powerful but can take more damage as well.
- All Your Powers Combined: The Final Boss is a bigger, meaner, spikier version of your character. It has many of the abilities you could obtain (namely your regular shot, laser, homing eyes, cancer bombs and homing bug missile), except stronger.
- Amazing Technicolor Battlefield: The Final Duel, in the center of a nuclear blast.
- Attack Drone: One of the evolutions you could obtain give you organic attack drones.
- Attack Its Weak Point: Almost all the bosses.
- The first boss, two lampreys, could only be damaged when its head was open.
- The second boss, a squid with an elastic head, was vulnerable in the eye.
- The third boss, a giant killer bird, was exposed to damage when it opened its mouth to fire out rings.
- The fourth boss, a crocodile-like reptile, was weak in its open mouth... when it surfaced to attack.
- The sixth boss, a nuclear reactor, was weak in the "nucleus" spot.
- The final boss was weak in all of its red "eyespots", killing all of them would defeat it.
- Awesome Yet Practical: Your "eat" move is this. Not only does it do a lot of damage, it also restores health for you and cancels out enemy projectiles. Plus, your score at the end of a level depends on how many times you hit the enemies with it.
- Battleship Raid: The Final Boss is a mini version of sorts. It has multiple targetable parts, five "eyes" and two horns. In order to defeat it, you had to destroy all its eyes. Destroying the horns would prevent it from using its lightning attack.
- Beware My Stinger Tail: One of the things your Eater could obtain was a stinger tail with dual spikes. Charging up your attack when you had a "poison tail" would act as a smart bomb.
- Big Eater: Justified, as your eater needs to well, eat to survive and evolve. Also, if your eater eats enough, it becomes a literal Big Eater.
- Biological Mashup: The fifth boss looks like a cross between a lion, a wild boar and a dinosaur.
- Breath Weapon: Your Eater's regular attack. Better to eat the opponent though, as it did more damage and could replenish your health.
- Charged Attack: Your regular attack could be charged by holding down the button. Depending on the tail you have, the shot would be different. If your eater evolved to get the "eyes" ability, you would also fire a circle of them out as Homing Projectiles.
- Collision Damage: Played straight.
- Critical Existence Failure: Averted. Your eater becomes small and scrawny if it takes too much damage, and a few more hits from enemies will kill it.
- Dual Boss: The first boss of the "Microbes" stage are a pair of lamprey-like organisms.
- Everything's Squishier with Cephalopods: The second boss, a squid with an extendable head.
- Evil Is Visceral: Your character, who looks like a mass of flesh if anything.
- Exclusively Evil: The eaters are implied to be this
- Extra Eyes: Some of the enemies have this characteristic, even creatures like jellyfish. Justified because the game takes place on a distant planet from Earth.
- Feathered Fiend: The third boss, a giant bird.
- Hitbox Dissonance: Your eater's weak point is the head and body. However, attacks that touch your tail or arms/legs are nullified.
- Horde of Alien Locusts: The eaters are a swarm of voracious aliens that consume everything in sight. You play as one of them.
- Hyperactive Metabolism: Eating enemies (or just taking bites out of them) will replenish your health (it does take quite a few bites though).
- I'm a Humanitarian: In the sixth stage, you get to fight against humanity. You can destroy their vehicles and eat them.
- Improbable Weapon User: You can use exploding cancer cells as an attack.
- Jungle Japes: The fourth stage "Reptiles" took place in a jungle with many hard-to-kill spiders and tortoise enemies.
- Kill'Em All: The Eaters do this to the world in the Bad Ending. They then proceed to move onto other planets to do the same...
- Lethal Lava Land: The fifth stage "Mammals" had your eater venture into a lava cavern, killing lots of armadillos and moles on the way.
- Lovecraftian Superpower: Some of the adaptations, if not the Mega Manning method itself, such as projectile eyes and weaponized cancer.
- Mega Manning: Your eater gains the characteristics of the enemies it eats. For example, eating a clam enemy will give your eater a hard shell, eating an energy-shooting enemy will give you lasers, etc.
- Mind Screw: The "good ending", where you beat the final boss, is actually the Bad Ending. The real good ending occurs when you lose against the final boss and choose not to continue.
- Mirror Boss: Sort of. The final boss is an eater similar to the player, and utilizes some moves that the player can use.
- Mix-and-Match Critters: The boss of Mammals is a green lion-boar hybrid.
- Never Smile At a Crocodile: Fourth boss is an alien crocodile that shot out homing spikes.
- Nice Job Breaking It, Player: If you beat the final boss. Earth gets doomed, along with many other planets.
- One-Hit-Point Wonder: Averted. Your Eater can have up to a maximum of 9 hit points, which can be replenished via eating enemies.
- Reactor Boss: The sixth boss, humanity's nuclear reactor. In a twist, you fight it from the outside.
- Secondary Fire: You eater's secondary attack was to launch its jaws out, eating weaker enemies and heavily damaging stronger ones. It's the only way to evolve new abilities as well as restore your health, by the way.
- Shock and Awe: The Final Boss has a move where his multiple spikes fire out electric balls off-screen. Each of them line up at either the top or bottom and then rain down extremely hard-to-avoid lightning beams. Thankfully, you can soften this move by destroying the spikes.
- Smart Bomb: Your Charged Attack becomes this if you have the poison tail.
- Spikes of Villainy: The Final Boss has them, and they are used for his That One Attack.
- Title Theme Drop: The Final Boss theme is the same as the title theme. Perhaps due to the fact that he's a meaner, stronger version of the player character.
- Underground Level: The fifth level "Mammals" had you go underground, fighting moles and armadillos on the way.
- Under the Sea: The second stage "Fish" takes place under the sea.
- Villain Protagonist: You play as a diabolical, amoral eater. The "good" ending that you get when beating the final boss actually says "BAD ENDING", meaning a bad end for humanity.
- X Meets Y: The Visitor meets Horizontal Scrolling Shooter.