As it happens, I'm not the first to look into this particular algorithm: the full listing of the decompression routine with some annotations is available on a Chinese blog.

I've already been able to write a "poor man's compressor" for it (well, with compression rate 0 so it actually increases the file size), but I'd like to know what algo it is. I suspect it's a readily available open source algo but I have no experience whatsoever with compression algorithms so I figured someone here might know more than I do about the topic.

I'm also attaching a small file packed with it. When decompressed, it's actually a resource file with some strings and a bitmap in it.

packed.zip

I believe I posted this topic in the wrong forum. Would any mod be so kind to move it to Technical Questions & Answers? Thanks in advance and sorry about this.

Code on that chinese site is incomplete. From a first look, it's a simple LZ-based algo but I can't say for sure without complete code.

But I'm quite sure I haven't seen this algo before.