Hikou no mizu is a free software project started in 2010, it aims to create a new fighting game for free operating systems.
It has two main goals.
Hikou no mizu is a free software, as in freedom, not as in free beer. The code is licensed under GPLv3 and the data is available under various free software licenses (mostly Free Art, but also OFL for fonts).
You are free and encouraged to copy, hack and redistribute hnm as much as you want :). And, if you made an improvement, consider sharing it on the forums !