Flyswatter I was designed after Breg Shaw survived the destruction of the Confederate battlecruiser Hoosier by zerg mutalisks. It was designed specifically for the destruction of mutalisks and their spire. It helped the mercenary in the destruction of a myriad of spires.
In 2505, Shaw was contacted by Bill Bousquette about a spire on the world of Choss. He set out, and met with the local Marshal Rin Shearon, bringing Flyswatter I with him. Rin had never seen a goliath before, but had read about them on the hypernet. She noted the many modifications he had done to the walker.
Shearon, Shaw and a Terran Dominion mutalisk expert named Brad Champlain set out to hunt the spire, with the extra weight of Champlain's equipment weighing down the Flyswatter I. The group was ambushed by mutalisks multiple times, but managed to ward them off. However, they were baiting the group, and were caught in a pincer that killed Shaw. Shearon launched the Flyswatter's missiles at the spire, and the backlash of acid blood killed off the mutalisks swarming around it. Shearon woke up with Champlain driving the Flyswatter, with the corpse of a scarred mutalisk in tow.
The Flyswatter I was a heavily modified version of the base Terran Dominion goliath. The usual twin smoothbore autocannons were replaced with Gatling-style chainguns on fully articulated arms complete with loader-claws, making them more effective against airborn targets. The missile pods were jury-rigged United Earth Directorate missile racks. The crotch-mounted swivel machine gun was replaced with a wraith burst laser.