The chests arn't placed fair, like Clbrend mentioned before.
Maybe you can place the start like this, like the real hunger games.
..............................................[Corn]
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...[] .......................................................................................[]........
......[].................................................................................. []..........
.........[] ...........................................................................[]..............
...........[] ......................................................................[].................
.............[] ..................................................................[]...................
...............[] .............................................................[]......................
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Okay, maybe this isnt working well on a forum, but you know what I mean.
If you place the tubes in some half circle and measure it it will be more fair.