The player is cast as Roger Samms, an entomologist planning to embezzle money from a research grant to escape his sordid life above an abandoned bar.

Roger, one of Eddie's tenants, has stolen a million dollars worth of loan money from a science corporation he had previously worked for and is planning to leave for Mexico City to start a new life.

But after a small argument with Eddie, he remembers a little trinket that he had gotten in his early childhood: a cockroach-patterned locket that belonged to his deceased mother, Angelina.

Upon its discovery, the locket transforms Roger's soul into a cockroach, and transports him to a mysterious sewer system connected to every section of the bar.

As the roach (Roger) explores a world filled with danger at every turn, including rats, garbage disposals, and his own pet cat, Franz, he is constantly being guided by his mother's spirit, who serves as an oracle.

Eddie has had just as bad a life, having his beloved wife die during childbirth and giving up his son out of grief and his livelihood stumbling.

During Roger's exploration, he is forced to extinguish the pilot light to a gas stove in the kitchen to save a baby cockroach that, in turn, assists him in jamming the garbage disposal with a spoon.

Roger must then set off a smoke detector to wake Eddie and then finally reach the locket in his own unconscious body's hand.

With both men safely out of the bar when it explodes, Roger and Eddie discover that they are, in fact, father and son, which was exactly as the oracle planned.

If both of them make it out, Eddie recognizes the cockroach locket (that contains a photo of Angelina) and they reconcile as re-united father and son before both reveal the truth about their past.

The family is reunited and they travel together to Mexico with the embezzled money, which Eddie uses to buy a new bar while Roger sets up a small lab to study roaches.

Bad Mojo's development was troubled: director Vinny Carrella noted that there was "a pall over the production" and "no happiness, just pain".

The original designer Drew Huffman came up with concept of having a small character in the gameplay due to the technical slowdowns on computers at the time.

[5] Huffman and Vincent Carella were brainstorming the game with Phill Simon taking inspirations from their experience with cockroach infestations, Franz Kafka's The Metamorphosis and the 1946 film It's a Wonderful Life.

"[30] A reviewer for Maximum opined that the game's unique and eerie story and presentation make it a compelling experience in spite of the limited gameplay.

[22] A reviewer for Next Generation commented that "Bad Mojo isn't the best graphic adventure, but it's got something that counts a long ways - peculiarity.