There are several places to play the board game Stratego online, including some unofficial sites where you can play Stratego-like games with interesting twists.
At Stratego.com, register with a new account or login with Facebook. You can play single player or multiplayer games. There are two versions available, Stratego Original with 40 pieces and Quick with 10 pieces. You can play against the computer, challenge your friends, or be matched with a similar ranking player. You can play a League Match to be counted for the Leagues and Ladders, with the top 250 players displayed. You get Battle Coins to purchase avatars, boards, and coats of arms, with the option to purchase more with real money at the Stratego Store.
Stratego Original at Gravon.net
Gravon.net is home to a number of online board games and card games, including Tichu, Balloon Cup, and Stratego Original. Much of the site is in English, although some of the text is in German. It's presented by Stratego Deutschland e.V. You can choose to play with European or American pieces.
Stratego on Facebook
You can play Stratego on Facebook, powered by Jumbo and Keesing Games. Choose a username and avatar to get started. You can play a single player match (full game or quick game), a ranked multiplayer match with 40 pieces each, or a Quick Arena multiplayer match with 10 pieces each. You must join Facebook to play.
Sabotage at ItsYourTurn.com
At ItsYourTurn.com, players can compete in the Stratego-like game Sabotage. Several clever variants are also available, including Mini Sabotage, Sabotage Rush, Corner Sabotage, and Sabotage Open Rush. There are differences from Stratego. You can win by doing one of three things: capturing your opponent's headquarters, capturing all of their movable pieces, or immobilizing your opponent so they can't make any moves. You don't know what any of your opponent's pieces are until your Recon piece exposes them.
Master of the Flag at Jayoogee.com
You can play a Stratego-like game, Master of the Flag, for free online against a computer at Jayoogee.com. They say their computer got top placements at the Computer Stratego World Championships for four years. It uses the same rules as the board game Stratego.
You can play free Stratego online at KeyGames.com. You'll have to endure a video ad first, It is the same Jumbo/Keesing game as at Facebook. You can log in with your Facebook account, or an existing or new Stratego account. If you want the same 3D action as the Facebook version without Facebook, this is a good option. If your browser doesn't give you the full window for the game on Facebook, it should fit into your window on KeyGames.com or FOG.com.
Fog.Com Free Stratego
This free Stratego online game is also the same Jumbo/Keesing game as on Facebook. It's another option if you prefer to play at this site rather than on Facebook. You can sign up for a FOG account or you can join the game using your Facebook login.
Gamerz.net / Richard's Play-by-eMail Server
Stratego can be played via email at Gamerz.net, home to Richard's Play-By-eMail Server.