Zapinator

Information
The Zapinator is the weapon mentioned by Blue as a weapon only owned by developers.

You could get this weapon before by cheating, but it has now been entirely removed from the game, since it was only for testing purposes.

It had infinite ammo, did 50 damage per hit, passed through enemies, and fired very quickly.

Trivia
It seemed to be a reference to the NES Zapper, through it's similar name and sprite.

Some users have reported finding it in random chests in the world. It is unknown wether this is a bug/easter egg or not. Video proof can be found here.