Elsewhere...

I'm not the only one who worked on the preservation of Overload. There are two other branches I encountered in the internet.

Handheld Fun

Something based on the PET version was available for the Psion Series 5 PDA. I can't find links any longer, but I definitely saw it. It claimed to be original, but obviously the Psion hit the market in 1997, 18 years after the first documented PET version...

Co-Evolution

Last but not least: Astatix Games have an excellent Windows cousin for sale. It looks great, and has 7 levels with dynamically changing rule variations. It even boasts a network multiplayer mode. There's a free shareware version for download, and for a modest $6.99 you can get the full version.