Some additional info about openlierox's license for those who are interested. According to the openlierox webpage, openlierox is the continuation of the opensource release of Liero Extreme under the zlib License. Unfortunately the sources distributed by openlierox do not seem to contain any of the original license info other then an old readme under the original_lx_docs dir which predates the opensource release. Liero extreme however was indeed released under the zlib License, as is cleary stated by its original author here: The openlierox work / extensions to Liero Xtreme are licensed under the GNU LGPL, see COPYING.lib . This is ok as the original zlib License is compatible with the (L)GPL, see: This means that openlierox as a whole is properly licensed, under the LGPL.