Part 1 was released in 2013, but was broken by the Steampipe 2016 update. It is officially not working at this point and no longer in development. There's a fix by Malortie, who managed to reverse engineer parts of the mod and get it running under Source SDK 2013. I am extremely grateful for his efforts - and while it is playable from start to finish - it's using binaries meant for HL2 so the AI, animations and weapons may not work as originally intended and I cannot officially support it. If you'd like to follow my latest project, Trepang2 is a spiritual sequel and you can try out the demo.
A demonstration of the headcrabs swarm based off the multi-core tech demo AI.