Earlier quoted context omitted.
Frozen Synapse is a simplified clone of Laser Squad Nemesis, which was done by... you guessed, the Gollops. Sadly that game is no longer available. It was multiplayer only (it had some single player but it was an afterthought) and they've taken it down long ago.
I played Frozen Synapse a bit. I seem to remember there were some local multiplayer options? Play by email would work ok for this kind of game. (But I don't think that was ever supported. Laser Squad Nemesis might have supported play-by-email, I'm not sure?)
Plus you could spend a day setting up your turn in a rated game against a good opponent, so who cared how the turns arrived.
Frozen Synapse decided to go with a time limit for turns... same mistake as xcom 2.