I've just released the PC version of my game Stellar Forces. It's a turn-based strategy game played against other players. The Android version has been going strong for over 7 years now, so I thought I'd port it across to the PC.
The game is free and similar to the mission bits of the original X-Com, or similar to Laser Squad (for those who go back that far). You take a turn, and then get an email when your opponent has taken a turn, so it's a very casual game and you take a turn when you can (some of us have jobs and kids!). There are over 100 missions now, and different types weapons and equipment meaning each game is different.
Download here: http://gamejolt.com/games/stellarforces/248481