Metalgun Slinger is a Game Boy Advance game released in Japan. While details regarding the plot and specific features are limited, the title strongly suggests that the game is a run-and-gun shooter, which is a common genre for handheld consoles, focusing on fast-paced action and shooting enemies.  The "Metal" prefix is also reminiscent of the popular Metal Slug series.

Metalgun Slinger (J)(Independent)

Metal Slug Advance (E)(TRSI)