Frozen synapse is one of the games I recommend through steam curators, it is a turn based strategy game played entirely online.
With different game modes from extermination of the other team, to hostage rescue, capture the flag and even a “how far do you think you can run accross the course before being eliminated” challenge there is quite a lot of gameplay on offer from this seemingly simple strategy game.
Play is formed accross usually 8 rounds, with planning phases for both teams and then the excecution is calculated online and shown before the next round of planning to hopefully lead to an outcome of victory for your own team.
There is a single player campaign but this isn’t the main draw of this game, and really you should see it for yourself to know if this is for you or not. Watch the video and make judgements for yourselves.
I definately recommend it and have got many hours of enjoyment from the game.