It shoots Bombs.
The Grenade Launcher is one of the many starting weapons. The use of the weapon is similar to throwing Bombs, however the projectiles have more velocity when shot. Just like Bombs, these projectiles will fall rather quickly. However, due to the increased velocity, the projectiles will roll much further if given the chance. This effect also works if the projectile is traveling up or down stairs. While it is a good weapon, it requires many upgrades to become effective. Killing flying enemies without items such as Gum and Skullito's Soul can be challenging. It is also worth mentioning that all items that affect Bombs affect the Grenade Launcher. The Powder Keg and Poison Bombs greatly improve the usefulness of the Grenade Launcher. Also, it should be noted that this is one of the two weapons the player can hurt themselves with, the other being the Rocket Launcher.