diff --git a/Board.py b/Board.py
index 84e2f63..44dd672 100644
--- a/Board.py
+++ b/Board.py
@@ -12,7 +12,13 @@ class Board:
 			self.state[field] = token
 			self.empty_fields.remove(field)
 		else:
-			print("This field's taken.")
+			print("This field's already taken. Choose another one.")
+			while field not in self.empty_fields:
+				field = int(input())
+				if field not in self.empty_fields:
+					print("This field's already taken. Choose another one.")
+			self.state[field] = token
+			self.empty_fields.remove(field)
 
 	def is_win(self, token):
 		if((self.state[0] == token and self.state[1] == token and self.state[2] == token) or
diff --git a/HumanPlayer.py b/HumanPlayer.py
new file mode 100644
index 0000000..70c3e03
--- /dev/null
+++ b/HumanPlayer.py
@@ -0,0 +1,8 @@
+from Player import Player
+
+class HumanPlayer(Player):
+	def __init__(self, token, name):
+		Player.__init__(self, token, name)
+
+	def choose_field(self, empty_fields):
+		return int(input())
\ No newline at end of file
diff --git a/Player.py b/Player.py
index cd915e4..5d7234d 100644
--- a/Player.py
+++ b/Player.py
@@ -3,7 +3,7 @@ import random
 class Player:
 	def __init__(self, token, name):
 		self.token = token 
-		self.name = name
+		self.name = name		 
 
-	def choose_random_field(self, empty_fields):
-		return random.choice(empty_fields)			 
+	def choose_field(self, empty_fields):
+		return random.choice(empty_fields)
diff --git a/RandomPlayer.py b/RandomPlayer.py
new file mode 100644
index 0000000..9140458
--- /dev/null
+++ b/RandomPlayer.py
@@ -0,0 +1,4 @@
+from Player import Player
+
+class RandomPlayer(Player):
+	pass
diff --git a/TicTacToe.py b/TicTacToe.py
index 078df99..59aa874 100644
--- a/TicTacToe.py
+++ b/TicTacToe.py
@@ -1,26 +1,42 @@
 from Player import Player
+from RandomPlayer import RandomPlayer
+from HumanPlayer import HumanPlayer
 from Board import Board
 
 class TicTacToe:
-	def __init__(self):
+	def __init__(self, player_x, player_o):
 		self.players = []
-		self.players.append( Player("X", "Player 1") )
-		self.players.append( Player("O", "Player 2") )
+		self.player_x = player_x
+		self.player_o = player_o
+
+		if self.player_x == "random":
+			self.players.append(RandomPlayer("X", "Player X"))
+		else:
+			self.players.append(HumanPlayer("X", "Player X"))
+
+		if self.player_o == "random":
+			self.players.append(RandomPlayer("O", "Player O"))
+		else:
+			self.players.append(HumanPlayer("O", "Player O"))
 
 	def run(self):
 		self.board = Board()
 		player = 0
 
+		if self.player_x == "human":
+			self.board.print()
+
 		while len(self.board.empty_fields) != 0:
-			self.board.make_move(self.players[player].token, self.players[player].choose_random_field(self.board.empty_fields))
+			self.board.make_move(self.players[player].token, self.players[player].choose_field(self.board.empty_fields))
+			self.board.print()
+
 			if self.board.is_win(self.players[player].token):
-				self.board.print()
 				print(self.players[player].name + " has won.\n")
 				break
-			if (player == 0):
+
+			if player == 0:
 				player = 1
 			else:
 				player = 0
 		else:
-			self.board.print()
-			print("It's a draw.\n")
+			print("It's a draw.")
\ No newline at end of file
diff --git a/main.py b/main.py
index c9009ad..0d5af3d 100644
--- a/main.py
+++ b/main.py
@@ -1,21 +1,48 @@
 import sys, getopt
 from TicTacToe import TicTacToe
 
-number_of_rounds = None
+games = None
+player_x = None
+player_o = None
+
 try:
-	opts, args = getopt.getopt(sys.argv[1:], "n:", ["numberofrounds="])
+	opts, args = getopt.getopt(sys.argv[1:], "n:", ["games="])
 except getopt.GetoptError:
-	print("main.py -n <numberofrounds>")
+	print('''
+		usage: main.py -n GAMES
+					   player_x player_o
+
+		positional arguments:
+		  player_x				Type of the X player [human|random]
+		  player_o				Type of the O player [human|random]
+
+		optional arguments:
+		  -n GAMES, --games GAMES
+		  						number of games to play 
+		''')
 	sys.exit(2)
 
-if(len(sys.argv) != 1):
+if((len(sys.argv) != 1) and (sys.argv[-2] in ("random", "human")) and (sys.argv[-1] in ("random", "human"))):
 	for opt, arg in opts:
 		if opt in ("-n", "--numberofrounds"):
-			number_of_rounds = arg
+			games = arg
+	player_x = sys.argv[-2]
+	player_o = sys.argv[-1]
 else:
-	print("main.py -n <numberofrounds>")
+	print('''
+		usage: main.py -n GAMES
+					   player_x player_o
+
+		positional arguments:
+		  player_x				Type of the X player [human|random]
+		  player_o				Type of the O player [human|random]
+
+		optional arguments:
+		  -n GAMES, --games GAMES
+		  						number of games to play 
+		''')
 	sys.exit()
 
-game = TicTacToe()
-for x in range(0, int(number_of_rounds)):
+game = TicTacToe(player_x, player_o)
+for x in range(0, int(games)):
 	game.run()
\ No newline at end of file