Manic Digger (3 Mb)
Description:
"Manic Digger is an Open-Source implementation of block-building games as made famous by Minecraft and (the now-discontinued) Infiniminer."
The game runs but the developer describes it as Pre-Alpha software.
Homepage:
http://sourceforge.net/projects/manicdigger/
Game's Blog:
http://manicdigger.sourceforge.net/news/
Download Page:
http://sourceforge.net/projects/manicdigger/files/
Link to Official Server:
http://fragmer.net/md/
Image: