Beast Rizer Plus

Petro+, pronounced Petro-Plus (ペトロプラス), is a 2D action-adventure game developed by Burst Arts Inc. and published by Multisoft exclusive for the WiiWare. This game was produced in commemoration of the Petropolis series' 15th anniversary. Because of this, the game homages the original classic games (from the first game to Petropolis 4), featuring fast-paced action gameplay.

Story
There are two stories in this game.

The first is the Giant Islander Siege Story, where the beastmen of Petro Islands are visited by five "Giant Islanders" (a term beastmen use to describe humans). Leading them is the emotionless Karlos, who orders the other four to build machines on most of the islands in order to obtain their resources. Witnessing this, Thunder informs three of his friends about what he saw and joined him on their new adventure to defeat the Giant Islanders.

The second is the Miracle Battler Adventure Story, where Pyro helps his older brother Quake make amends for the events of Petropolis 3, but Zero One shows up, having survived the crash of Dr. Shinichiro's UFO. As he goes after the Great Orb, the brothers unlock Prison Orbs, which release the beastmen inside of them. In exchange for being freed they help Pyro and Quake deal with the rebuilt Zero One and his army of alien-robots.

Playable

 * Thunder Storminski
 * Selene Melodia
 * Milton Redder
 * Spike Sparks

Non-Playable

 * Jessica Magnets: A strict yet beautiful businesswoman in charge of her father's electrical company. She now resides in the Southwestern Islands, hoping that she could use their resources to improve the state of her company.
 * Abel Crones: A professional sniper who was once reported MIA during a war on one of the Giant Islands. He is now located in the Northern Glaciers, likely to seek the weapons hidden in the frozen clumps of ice
 * Marsha Price: An innocent princess who is about to rule a kingdom from her Giant Island home. However, she choses to control the Eastern Islands, where she feels she would be more suitable as royalty here.
 * Thomson Higgins: An intelligent yet inept engineer who plans to make a change in his life. To start, he choses to stay in the Azure Islands, where he analyzes the data of the Power Shooters in order to create his own.
 * Karlos: A human who is the enigmatic leader of the Giant Islanders invading, as well as the main antagonist. Despite his brilliance at a young age, his parents gave him little attention and he spent most of his childhood alone. In his adult years he became embittered and after feeling nothing but sadness and anger during his youth he decided to create a world of nothingness, starting with the Petro Islands. He resides on the Central Islands.

Playable

 * Pyro
 * Quake
 * Isaac Flare
 * Samantha Koala: a koala singer with magical powers. Samantha was born to Herbert and Isabella Koala, her father dying during her youth. She met a lavender Faerie from Hispark Island which gave her the magical abilities she has now. She was captured by Zero One's robotic soldiers during the invasion of Miracle Kingdom, but then saved by the dragon brothers, who she joins afterwards. Samantha's powers all come from the lavender faerie she rescued long ago, and without her, she loses them temporarily.
 * Atlas Turner & Sammy Snail: A young tanuki with a snail morphman. Atlas was born in the Floral Islands to a family of scientists, but was raised by his grandfather. He meets Sammy, who was with his grandfather for years. Atlas decided to own him, but then, a cannon formed on the tanuki's arm. Eventually, when he was captured by the Zero Army, he used Sammy to try and bust themselves out. That was when they met the dragon brothers and Samantha, who join them in their battle against the robots. Atlas uses Sammy as his main weapon source during battle.
 * Felicia Tapir: A wealthy tapir woman who has ties to the royal family of Quartz. Her mansion was raided by the Zero Army, who then decided to capture her as they continued their domination. She was rescued by the Miracle Battlers and chose to assist them in battle. Apparently, she wields a machine gun, which she uses only for emergencies. Felicia is also in a relationship with Bobo Otter.
 * Bobo Otter: A middle-aged sea otter who worked alongside Grove's father. While cruising the oceans of the Miracle Kingdom, he was ambushed by the Zero Army and captured later on. He was then rescued by the Miracle Battlers and he joins them afterwards. As a sailor, Bobo fights with an anchor, but also relies on physical combat. He is engaged with Felicia Tapir.
 * Motor: A squid-like creature who escaped from the Zero Army. He has no specific origin, but he was known to control the minds of other beastmen, giving him the alias of "Hacker." He proved this by braimwashing most of the Zero army to help fight for the Miracle Battlers.
 * Milan Absolute: A feline who works as a spy. She eavesdropped on the Zero Army's intentions with the Miracle Kingdom and went to report it to the dragon brothers. But Zero One learns of Milan's infiltration and attempts to terminate her himself. She is known to have many abilities as not just a spy, but also a traveler similar to Thunder himself.

Non-Playable

 * Zero One: The main antagonist of the game and the final boss. Like in Petropolis 2, he  has two different phases. The 1st phase is him fighting in his normal body, occasionally switching into other beastman forms. His 2nd phase is a gigantic version of himself with alien attributes to his armor, making him more threatening.