Because you can't find it anywhere else

The Great Comparison

The Translocator: The translocator was originally created by the Liandri Mining Corporation to allow the workers to be able to escape in the event of a cave in. The translocator is a disc, that fits into a launcher and can be launched in for a great distance in any direction.

Pros: This gun can be fire fired anywhere, and with a little clever use of physics can allow the user to a very wide range of transport. As the translocator forcibly places the person in the area of the disc, anything else that is there is vaporized. This makes the translocator a somewhat unique weapon.  The translocator can be opened anywhere (in midflight, under water, in a teleport, etc..), allowing the user to hop around quickly.

Cons: The translocator can only be used by the person wielding it, and it is a one way trip. To get back, the disc must be relaunched. The translocator has a terrible aversion to a person carrying a flag while using it. It looks ugly as all hell.

The Portal Gun: The portal gun is a hand held device produced by the Aperture Science Center. This gun can fire two “portals”, one orange and one blue, that open a gateway between each other. It can pick up and carry objects.

Pros: After the portal ends are set, anything and anyone can go through them. Single ends of the portal can be manipulated independently of each other, which coupled with the fact momentum of objects is conserved through the portal, allows the user to propel themselves wherever they please (this of course, takes a certain amount of skill and a high tolerance for pain). It is aesthetically appealing

Cons: Because the portal gun is so contrary to our perception of physics,  it is very easy to mess up while using it. VERY EASY. The user has to have a visible line between them and the desired portal position, which makes portal placement limited. In addition, the portal itself is a passive and nonviolent entity, even though it could be used indirectly for violent purposes (such as dropping blocks on people, making them fall until they reach terminal velocity and catch fire, launching them into the sun, etc..).

Author’s choice:  Both? I don’t know they both have their purposes, and having a translocator I could fire through a portal would be sweet.

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