Tankar om mitt tre-i-rad spel i C++?

/* Tic tac toe game */
#include <iostream>

/* Clearing the tty */
#define CLEAR (std::cout << "\033[2J\033[;H") //ANSI escape sequence to clear tty

class Game
{
private:
	char boards[9] = {' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '};
public:
	Game() {}
	void drawGame()
	{
		for (int i=0; i<9; i++) {
			if (i%3==0 && i!=0)
				std::cout << '\n';
			std::cout << '[' << boards[i] << ']';
		} 
	}
	bool hasWon(char player)
	{
		#define IS_PLAYER(i) boards[i] == player
		
		/* Vertical checks */
		if (IS_PLAYER(0) && IS_PLAYER(1) && IS_PLAYER(2))
			return true;
		else if (IS_PLAYER(3) && IS_PLAYER(4) && IS_PLAYER(5))
			return true;
		else if (IS_PLAYER(6) && IS_PLAYER(7) && IS_PLAYER(8))	
			return true;
		/* Horizontal checks */
		else if (IS_PLAYER(0) && IS_PLAYER(3) && IS_PLAYER(6))
			return true;
		else if (IS_PLAYER(1) && IS_PLAYER(4) && IS_PLAYER(7))
			return true;
		else if (IS_PLAYER(2) && IS_PLAYER(5) && IS_PLAYER(8))
			return true;
		/* Cross checks */	
		else if (IS_PLAYER(2) && IS_PLAYER(4) && IS_PLAYER(6))
			return true;
		else if (IS_PLAYER(0) && IS_PLAYER(4) && IS_PLAYER(8))
			return true;
		
		return false;
	}
	void setBoard(int i, char x) {boards[i] = x;}
	bool isSet(int i) {return (boards[i] == ' ' ? false : true);}
};

char nextPlayer(char player) {return (player == 'X' ? 'O' : 'X');}

int main(void)
{
	Game game;
	
	std::cout << "Hi! Welcome to this tac-tac-toe game!\n";
	std::cout << "X will start to make a move, then O.\n\n";
	
	/* Game logic */
	char player='X';
	
	do {
		short board;
		game.drawGame(); std::cout << '\n';
		
		std::cout << player << ", pick a board number (1 - 9): ";
		std::cin >> board;
		if (board <= 0 || board > 9) {
			CLEAR;
			std::cout << "Out of range, try again!!\n\n";
			continue;
		}
		if (game.isSet(board-1)) {
			CLEAR;
			std::cout << "Oops, board " << board << " is already occupied.. Try again!\n\n";
			continue;
		}
		game.setBoard(board-1,player);
		CLEAR;
		player = (nextPlayer(player));
	} while (!game.hasWon('X') && !game.hasWon('O'));
	
	game.drawGame();
	std::cout << "\nThree in a row! Congrats player " << nextPlayer(player) << ", you won!!\n";
	exit(EXIT_SUCCESS);
}