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.
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. You navigate the guide as a webpage.