What shape would the arcade classic Asteroids' universe be?

[Blue_Jaunte]

I heard this puzzle on the MathFactor podcast (which I highly recommend).

If you don't know what Asteroids is (somehow), here's a youtube video:

If you fly off the right side, you reappear on the left side, and vice versa. If you fly past through the bottom, you reappear at the top, and vice versa.

So, if this were a Universe, what would the shape be?
a. A sphere
b. A torus
c. A cylinder

I made a pictorial solution which I'll post after a few people have responded.

 

[Borek]

Too obvious, really undoubtedly simple.

 

[quasar987]

Hello Blue_Jaunte,

This is a fairly classic example\problem and probably many people know the answer but I am interested in seeing the solution you came up with.

 

[Blue_Jaunte]

Sorry for the late reply, Quasar. I replied earlier, but I was reported for a well-deserved insult. Here is my solution:
http://s78.photobucket.com/albums/j83/reclusivesage/?action=view&current=Asteroidssoln.jpg

 

[DaveC426913]

Correct.

 

[Borek]

Obviously my answer was too clever and has been wasted.

 

[Gokul43201]

Obviously my answer was too clever and has been wasted.

Not everyone is into acrostics.

 

[DaveC426913]

Obviously my answer was too clever and has been wasted.

Ha ha. Right over my head.