Mud River is a 2D arcade game in horizontal Shoot'em Up style, single player, in which the player controls a spaceship with the objective of destroying enemies. With two main weapons with infinite ammo and three secondary weapons that can be used according to the amount of power spheres the player can collect. The game has three levels with challenges and achievements to unlock.

Thousands of years ago, Pacal the Great abandoned Planet Earth by means of his Vimana spacecraft to escape the flood. But now, Pacal is back to search for the precious artifacts that were hidden in America.

However, ancient holy temples have turned into hostile polluting industries run by the ambitious Dr. Wellin, who is unwilling to give up his domains and resources. His power is absolute!

Pacal is enraged at the desecration of sacred sites and the destruction of the environment. He connects with an artificial intelligence known as Zacharias, which will help him fulfill seven missions and save terrestrial biodiversity. But Zach knows there is an evil force behind Dr. Wellin's terrible deeds. Is it an ancient god enemy of Pacal?

The Rio Doce (sweet river) was a paradise for mankind and animals, but now it has become a territory destroyed by the unscrupulous activities of Dr. Wellin. This is Pacal's first destination, going up the Rio Doce preventing its complete destruction, passing through the trails of fire until reaching the Domo, laboratory of the nefarious villain, to recover the sacred relic stolen from the ancient Krenak people.