From Fedora Project Wiki
This license is only free when used by Magnus on Teeworlds. Normally, clause 4 would be a problem, but in this case, we've confirmed with Magnus that clause 4 can be met by bundling with a trivial "helloworld" program. With other programs, we would not have that intent, so it would be non-free.
Copyright (C) 2007-2008 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. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution. 4. Neither this software nor any of its individual components, in original or modified versions, may be sold by itself.