Wonderful World is a FM2K indie fighter made by Ainefill. If you would like to see some footage to give you an idea of what gameplay is like, you can search for videos on nicovideo or youtube with the phrases "WonderfulWorld" and "wonderful world <character name>" respectively.
While the game is not yet in it's final version (currently 0.71), the game has tournament play in Japan and is pretty well balanced. Unless it's a test version, you can consider any given of Wonderful World a complete game.
Currently the scene outside of Japan consists mostly of people playing online using Lunaport as well as some people who play locals offline. Discussion and matchmaking normally happens in the #WW channel on irc.mizuumi.net, or in the Wonderful World Thread on Dustloop. The community is still relatively small, so please feel free to help us fill out the remaining information on the wiki.
You may also view more details about the game by looking at the official guide packaged with the game. To view it, open the "説明書" folder in the Wonderful World folder and double click wanindex.html to open it in your browser.