This is a rarely known file format. But I happen to be trying it out today. It turns out to be a very good for story-telling file format. The player is hard to find also. Every file-format sites I've found had no idea about how to play or open up this file. But 7-zip seems to be able to decompress AVT, although that was not what I want.
To play AVT file, you need to download akfavatar-0.18.0.bin.w32.zip from http://akfavatar.nongnu.org/.
It is listed on freshmeat also: http://freshmeat.net/projects/akfavatar.
