Not sure if a lot of people know about this, and I also don’t know when they will run out. So you’re welcome if you actually care for this game. https://www.pcgamer.com/2014/06/25/we-have-one-million-spacechem-steam-keys-to-give-away-with-bundle-stars/
If you didn’t know, some achievements in this game unlock some spacial TF2 items.
Yes, I’ve wanted to have this game just to unlock Fishcake in TF2. Now I have it for free 
Lol I’m pretty sure everyone only wants the game for the TF2 items.
Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.