This software called "zCatch/TeeVi" is a modification of "zCatch" which is a modification of "Teeworlds". See license.txt.

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The following is the content of the readme.txt distributed with zCatch:
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Copyright (c) 2015 Magnus Auvinen

This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.

Please visit http://www.teeworlds.com for up-to-date information about the game, including new versions, custom maps and much more.