That gun turret used to be the only thing that stood between us and the desert's cruel kiss...”— Kleiver, Jak 3
The Spargus gun turret is a weapon in Jak 3 found at the mouth of Spargus' shore. It was used to protect Spargus from any threats from the Wasteland, and was primarily maintained by Kleiver, who was the prime gunner of the city, before handing the title to Jak after he beat his record.
The turret is a large, metal-plated, heavily armored, dual-cannon weapon mounted atop of a large concrete tower at the mouth of the bay. It has a protected seat (similar to the gunpod) which allows for protection of the gunner, however the turret itself has a limited durability. It is possible to see rough explosions at the bottom of the screen during gameplay, suggesting the turrets mechanics are located somewhere at the bottom of the tower.
During Jak 3, an objective "Beat turret challenge" is received from Kleiver in the form of a challenge; if Jak can beat Kleiver's high score shooting colored disks, he will give Jak a light eco crystal, as a reward. Up until this point, Kleiver had been the "tall puppy" of the turret, a title passed on to Jak after he beat it.
Later in the game Spargus was attacked by Dark Maker walkers, in the mission "Defend Spargus from attack", where the top gunner (Jak) was then called upon to defend the city. Once the Dark Makers were successfully repelled, Jak climbed out of the turret to meet Damas and Kleiver at the bottom. Damas then congratulates Jak on the victory, where he was presented with his final war amulet and a gift of Mar's chest armor.
The Spargus Turret Game involves target practice where you have to hit enough targets to reach a certain score limit and earn Precursor orbs.