Everybody remembers this paper-and-pencil game from childhood: Tic-Tac-Toe, also known as Noughts and crosses or Xs and Os. A single mistake usually costs you the game, but thankfully it is simple enough that most players discover the best strategy quickly. Let’s program Tic-Tac-Toe and get playing! Learning outcomes After finishing this project, you'll get to know a lot about planning and developing a complex program from scratch, using methods, handling errors, and processing user input.