Goo Gun

The Goo Gun was a weapon seen in the original Blur Teaser for Fuse, and was Izzy's signature weapon at the time. It operated by firing small globs of an unknown black substance at high velocity like a shotgun. When this glob impacted an object, it stuck to it and appeared to grow around the target, rapidly expanding to crush it (enough to break the visor of a troop it was shot at). In the teaser it also forced a troop back into a wall, which he is then stuck to. When shot at by Jacob's Tesla Bow, the substance exploded in a fireball, hinting at co-op gameplay that plays a large focus in Fuse. The actual name of the gun was never finalized during development, although Glue Gun and Goo Gun were used. Spider was also considered, likely because the growing arms of goo around a target looked like spider legs.

Behind the Scenes
After the Blur Teaser was released, Insomniac Games decided that the Goo Gun lacked the punch needed to make it feel distinctive and unique, and made efforts to change it. The final result of this change is the Shattergun, which encases enemies in rapidly growing Melanite. Despite the very different appearances, the basic concept is the same; enemies are immobilized by a substance that rapidly increases in size, leaving them open for a quick kill. Despite this, the Shattergun has one advantage over the Goo Gun: it raises enemies above cover.

Trivia
When the Blur Teaser was released, the Goo Gun was compared by many viewers to a sequence from Pixar's The Incredibles. In the film is a scene where the main character, Mr. Incredible, is captured by way of turrets firing a sticky black substance that rapidly expands, and is able to defeat him via immobolization. While the substance doesn't appear to have any crushing abilities like what the Goo Gun fires, it is sufficiently adhesive to overcome even Mr. Incredible's super strength.