Like the original, players venture to defeat the mad scientist Dr. Robotnik, who plots to turn the animal population of the fictional South Island into evil robots.

The game follows the player's quest to defeat Dr. Robotnik, who has converted all the animals of South Island into evil robots.

[7] Although Somari borrows the concepts for its game dynamics from the original Sonic the Hedgehog, the implementation of them differs in many ways.

The audio of the game is similar to the original, but suffers from a poor conversion to the NES's sound system.

[11] It is unknown precisely how, when, or where the game was created,[5] though Asia is likely;[8] a Taiwanese trademark for "Somari" was registered on March 1, 1994.

[16] Although Somari does not feature both characters in the same game, the fact that Mario had been placed into the world of Sonic the Hedgehog was registered with astonishment.

[3]: 26 GamesRadar listed Somari on their list of "Crazy ass rom hacks", calling it "Less mash-up and more train wreck" due to poor physics and unresponsive controls, and recommended that players instead purchase Super Smash Bros. Brawl if they wished for a crossover featuring Mario and Sonic.

[4] GameSpy, however, described the game as "a remarkably good port/hack of Sonic to the NES,"[5] and Atari HQ described it as "amazing[ly] original" with "more than adequate[]" level-porting.