Two players taking turns doesn't involve multithreading.
Your game does one thing at a time:
1. initialize
2. while (not finished)
3. get player 1's input
4. process player 1's input
5. if (not finished)
6. get player 1's input
7. process player 1's input
8. if (finished)
9. end the game
Concurrency means doing more than one thing at the same time.