Twins Juno and Vela, and their dog Lupus, are Jet Force Gemini, intergalactic police.
Their mission? Stop the evil space bug, Mizar, from his goal of galactic conquest with his seemingly-infinite army of Drones. They'll have to stop along multiple planets along the way, and assisting King Jeff and rescuing his subjects, the Tribals.
Jet Force Gemini is a third-person shooter which revels in making gigantic creepy bugs explode into dribbly mucousy bits. The Jet Force team are given progressively more powerful weapons, from the Machine Gun, which rips through both enemies and ammo, the Plasma Shotgun, which you can charge up for some explosive fireworks, and the Tri-Rocket Launcher, which fires three rockets with every shot, sending explosive doom in the direction of your target. There's also the Fish Food, which is used to...er, feed fish. Really.
Even though they're called Drones, these bugs aren't stupid. When encountered, they'll rush you, hide behind objects for cover, and even run off for reinforcements when you confront them. They also take delight in shooting the innocent Tribals, whom you are supposed to be rescuing. But the Drones are nothing compared to the game's insanely difficult bosses, which includes a pair of gigantic praying mantis, a huge beetle, and of course, Mizar himself, to name but a few.
Each of their team has their own special abilities - Juno can walk through lava without any trouble, Vela can swim underwater, and Lupus can hover for short distances and travel through tight spaces. These abilities are required to fully access areas that they previously couldn't reach. The team also get the help of Floyd the Droid, a hovering robot that can be controlled by player two as a floating gun with infinite ammo when he joins your team.
The game also includes three different multiplayer modes: Battle - featuring most options of an average First Person Shooter but with a third-person perspective, Target Shoot - a shooting gallery with a first-person view, and Racing, which includes some kart-like racing as well as old-school top down racing games.