It is completely free because it is open source.

What is Dana?
DAna is The Connect4(Connect Four) Online game you must have!! This game is designed mainly for playing online with your friends. It also has Velena AI Engine(Perfect Play) and Ana(Moderate) to play against. Its got a simple elegant Chat Window also!!!

Screenshots
You can check out some screenshots at sourceforge screenshots section

Development
Dana Source
DAna is written in C++ using wxWidgets 2.6.3 for GUI and Raknet 2.5172 for networking. It was done as a Hobby project by Darshan M Sonde and Amith Raravi. Darshan had started the project by doing the initial framework using wxWidgets. Networking capabilities including a chat window was added by Amith using Raknet 2.5172. And also the game was brought to the Production/Stable state by Amith. The project is an ongoing effort to better understand wxWidgets and Raknet and to write programs efficiently using these afore-mentioned open source software.

As of today further development is stopped as it has reached stable state.

New features requested by the users will be added upon consideration by the project administrators.

For more information about the dana project please visit the sourceforge project page

About
Object
The object of game is simple - be the first to connect 4 dots (in a line of course) :)

Rules
The rules of Connect Four game are as follows. Each player takes turns in dropping discs into a vertical grid. A player can drop a disc into a column only if that column has at least one empty location in it. Play continues until one of the player wins or all locations on the grid are filled up upon which the game is declared a draw.

Playing against the Ana Engine
The Ana Engine was developed by Amith Raravi during the previous year. Its a moderate play engine. It is very near to humans in its look-ahead capabilities and takes sometime to reply. Its an engine to be played against by beginners and intermediate players. Its a good engine to practice your game.

By default you will play First against the Ana Engine. To play, click File->New and a new game will start. Click Edit->Play to play either First or Second. You can take back moves by clicking on Edit->Undo and entering the number of moves.

Playing against the Velena Engine
The Velena Engine is a Connect Four AI Engine written by Giuliano Bertoletti based on the knowledged approach of Victor Allis. Its a perfect play engine. With perfect play, the first player can force a win by starting in the middle column. Starting in the two adjacent columns allows the second player to reach a draw; starting with the four outer columns even allows the second player to force a win. This engine is meant for experts only. It will never make a mistake. So you either play the right move or you lose.

If you want to play against the Velena Engine then click Edit->Play against->Velena and you can start a game against Velena. By default you will play First. Click Edit->Play to play either First or Second. You can take back moves by clicking on Edit->Undo and entering the number of moves.

Playing Online against a friend
To play online against a friend, one of you have to start a server version by clicking on Network->Start Server and entering the server name. The other person has to start the client version by clicking on Network->Start Client and entering the client name and then the IP ADDRESS of the server. After connecting each of you will see the others name being displayed. Any one of can start a game by clicking on File->New and a new game will start.

NOTE : If you donít know the server IP ADDRESS then the person running the server version can go to http://www.whatismyipaddress.com. In this site your IP ADDRESS will be displayed. Send it to the one running the client version using any chat service such as Google Talk, Yahoo Messenger, MSN Messenger etc. My pick is Google Talk which can be downloaded from http://www.google.com/talk.

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