It took me a little exploration to figure out why this game was removed from Steam, and I think - I haven't played Frozen Synapse, so I'm not sure - that when the game's multiplayer servers were shut down a couple of years ago there wasn't any reason to sell a version of the game featuring multiplayer play. The base game is still around, and this one contains the single-player part of things, in a revamped version, as well as the non-working remains of multiplayer. I think.

This is an old key, recently revealed. Please note that since this game is no longer sold on Steam, I can't fix or replace it if something goes amiss. However, the key was just revealed and should be like new.