Altered Beast: Guardian of the Realms was released in late 2002 by now defunct 3d6 Games for the Game Boy Advance.
This is a side-scrolling game similar to the first Altered Beast.. You have to fight through each level to the boss while collecting spirit balls to transform. New to this game is the addition of power ups. There are 15 stages. The game highly encourages replaying stages to get stronger forms of each beast and to rack up extra lives and continues. This game drops the infinite continues given by the Genesis version. There is also multiplayer accessed by linking multiple GBAs.
The story is a battle between Zeus and Arcanon. The Dark Reaper Arcanon has invaded the gateway to the realms, and has defeated each guardian. He is planning to use each to build up his army to try to take over the Realm of the Gods to defeat Zeus and rule over the realms. Zeus resurrects you to defeat Arcanon's gatekeepers to regain the key to each realm. Arcanon has also scattered the spirits of the guardians and put them in the possession of ghosts throughout each level.
Similar to the first game, you start off being resurrected by Zeus. This stage is a cemetery filled with zombies and trolls. The beast of this level is the Canis (Wolfman). The boss of the level is an giant undead Centurion warrior that throws shields at you and shoots lasers. He is defeated by destroying the columns of the pavilion he is in, causing it to come crushing down on him.
An underground cavern filled with spider beings and giant worms. Your beast form in this game is the Nagi (Snakeman). The boss of Dubari is a massive earthworm, defeated by attacking when he isn't shooting fire.
A swamp which was used as an execution ground. There will be executioner enemies and also lizards and wasps. The beast form in this level is Draco (the Dragon). The boss of this level is a hydra that is able to regenerate if the head and neck are not completely destroyed.
A desert world that is periodically hit by a sandstorm which pushes your character forward. There are rodents and deadly beetles. The beast form in this level is the Smilodon (Tiger). The boss of Sahar is a giant ant queen that shoots little ants at you while flying back and forth.
A lush jungle that is filled with dangerous plants and insects. It will occasionally rain, slowing you down and hampering your attacks. The beast form in this level is the Terapis (Turtle). The boss of this level is a giant flower that shoots seeds at you and causes vines to come from above and below.
An underwater world which oddly seems to be somewhat based on more modern times (See the sunken cruise ship in the background). There are various fish enemies and seahorses that can freeze you. The beast form of the level is the Charodon (Shark). Once you transform you are able to freely swim, and the stage opens up so you can go way higher or lower. The boss here is a squid/jellyfish creature that has overtaken a sunken ship.
Ruins located in the middle of the jungle. This is the first stage to implement bottomless pits. This stage has mostly undead warriors and some insects. The beast form of this level is the Cerathos (Rhino). The boss of Despot is a Tribal demon that is able to shoot multiple types of attacks that can easily kill you in one shot.
This is a very destructive area, filled with magma and broken pieces of land. There are many golems that inhabit this level, along with the occasional flying demon. The beast form in this level is the Scorpios (Scorpion). The boss of this stage is a giant lava golem that can rain meteors from the sky and teleport by melting into the ground.
A sky temple that eventually becomes a full on aerial stage once you transform. Most of the enemies here are cherub demons with the occasional flying squid. The beast form in this level is the Avion (Eagle) which can fly. The boss of this level is a giant demon that throws daggers at you, and once you do enough damage, he will bring out a flame sword.
This level is a crystal cave that has a lot of obstacles. The enemies in this stage consist of crab demons and warriors. The Canis returns as the beast form in this stage. The boss here is a giant horned skeleton.
After completing the last level, Arcanon decrees that you have been banished, so you are sent here. This is a very abstract wasteland with floating temples and ruins. Most of the enemies are from previous stages, like the beetles and snakes. Like the previous stage, the beast is one from an earlier stage, the Terapis. The boss here is an underground demon that constantly burrows and resurfaces while throwing rocks.
Continuing the theme from the last level, this is an even more desolate wasteland. Reminiscent of a dried out ocean with the fish skeletons on the ground. But the enemies are mostly fish. The beast form in this level is the Charodon. Once you transform, this nonsensically turns into an underwater style level with swimming. The boss here is a giant brain that fights even as you destroy pieces of it.
A somewhat virtual reality inspired realm with a giant wormhole in the middle. The enemies are snake warriors and flying beasts. The beast from of the level is the Draco. The boss here is an angel who summons many cherub angels. She also has the ability to freeze time.
Another abstract level with spirts floating all over. With pillars strewn everywhere. The unicorn enemies from Altered Beast return with a vengeance along with two headed bears. The beast in this level is the Chimera. The boss is a giant heart that you must destroy piece by piece.
Palace of the Gods
As the title implies, this is a palace where your final showdown with Arcanon takes place. You start off the level as the Chimera, and the only thing on this level is the boss battle with Arcanon. He can teleport and freeze you with rays of light. There are a few enemies but the main focus is Arcanon.
Like in the original game, you transform into a beast after you collect three of the spirit balls. Each beast has two attack types. Most of the time this will be a projectile attack and a dash attack. At the end of the stage you will revert back to your beast form. This game also has multiple forms of each beast. Once you complete a stage, you can replay a level to try to get a talisman. The talisman will unlock the other form of the beast, which is nothing more than a palate swap. You are able to use the alternate forms in multiplayer.
Canis- Wolf Form
Canis is the beast form for the Crete and Thundaga stages. The primary attack is a fireball, and the secondary attack is a straight horizontal dash that kills any enemy in the way. The alternate forms are the Arctic Canis, the Obsidian Canis, and the Golden Canis.
Nagi- Snake Form
Nagi is the beast form for the Dubari level. The primary attack is to spit acid, the secondary attack is a rolling dash. The alternate forms for the Nagi are the Diamond Nagi, the Ruby Nagi, and the Emerald Nagi.
Draco- Dragon Form
Draco is the beast for Lerna and the Chaos Realm. The Draco has the ability to fly to a certain extent. The Draco shoots a lightning bolt as it's primary attack, and surrounds his body with electricity for the other attack. The alternate forms are the Metallic Draco, the Crystalline Draco, and the Alpha Draco.
Smilodon- Tiger Form
The Smilodon is the beast form of the Sahar level. The Smilodon shoots a fireball for it's primary attack, and the secondary attack is a vertical dash consumed in fire. The alternate forms are the Sumatra Tiger, the Corbetti Tiger, and the White Tiger.
Terapis- Turtle Form
The Terapis is the beast for the Organica and Mojave levels. The attacks are a shockwave blast from it's mouth and a rolling dash. The alternate forms for the Terapis are Ankie, Steggie, and Trudy.
Charadon- Shark Form
The Charadon is the beast of Oceanus and Parcha. This beast has the ability to swim freely, allowing it to explore the entire stage. The primary attack is a blast attack and the secondary attack is a rolling dash. The alternate forms are the Leopard Charadon, the Panther Charadon, and the Tiger Charadon.
Cerathos- Rhinoceros Form
The Cerathos is the beast form in Despot. The primary attack is a shockwave, and the secondary is a charge attack. The charge attack is a problem on the stage because of the multiple pitfalls. The alternate forms for the Cerathos are the Steel, Iron, and Titanium Cerathos.
Scorpios- Scorpion Form
The Scorpios is the beast form of Vulcan. The primary attack is a claw attack. It's secondary attack is a downward laser beam. The alternate forms of it is the Sand Scorpios, Rock Scorpios, and the Ice Scorpios.
Avion- Eagle Form
The Avion is the guardian beast of Haven. The Avion can fly freely, which controls the same way as the Charodon. The primary attack is a short-range tornado attack, and the secondary attack is a spinning beam attack. The alternate forms are the White Avion, the Night Avion, and the Fire Avion.
Chimera- Ultimate Form
The Chimera is the beast of the Dreamscape. You also use the Chimera in the final battle against Arcanon in the Palace of the Gods. The primary attack of the Chimera is a normal punch with no special abilities, but the secondary attack is a sound blast attack. The alternate forms are the Mega Chimera, the Chimera Lord, and the Giga Chimera.
There are many temporary powerup items in the game. They can be found in breakable items or from certain enemies.
Ambrosia- Fully heals you. The most common power-up.
Regenerate- Your life regenerates for a short amount of time.
Inner Fire- Fire will shoot out from you, damages enemies close up to you.
Zander's Shield- Spinning barrier that damages enemies, but does not protect you from damage.
Determination- You will not take any damage.
Adrenaline- Increases your speed.
Berserk- Increases damage.
Venom- Punches poison enemies, doing more damage.
Shockwave- A wave of energy moves outward from you, damaging enemies.
Earthquake- Kills all enemies on the ground.
Armageddon- Kills all enemies.