DotA is not a standalone game. It exists currently* as a custom map modification of Blizzard Entertainment's Warcraft III: Reign of Chaos and it's expansion The Frozen Throne on both PC and Macintosh. Therefore, the very first requirement to play DotA is to own a copy of both games, preferably the BattleChest edition.
The link above will bring you to Blizzard's Store's page for the Warcraft III BattleChest. Alternatively you may source for original copies over the Internet, e.g. eBay, Amazon, or your local game stores' bargain bins for physical copies.
Once you've obtained for yourself a copy of both games we can begin the installation process. This guide assumes you have already have a working connection to the Internet (otherwise how are you even reading this right now?)
Step 1-1: Installing Reign of Chaos (RoC) and The Frozen Throne (TFT) using physical CDs on PC
The following instructions are for owners of physical disk copies of the games. You can also purchase the Warcraft 3 ROC and TFT Installers from the Blizzard website.
a) Installing RoC
i. Place the game disc (if you're using it) into your CD drive. If nothing happens on your screen, Autorun has been disabled. In this case go to My Computer, and double click the icon of the drive containing the CD. That should bring up the installer:
ii. Upon agreeing to the Terms and Conditions of the EULA, you will have to enter your name and CD-key, which is found on the jewel case of the game:
iii. The installer will now ask you to select a directory to install the game in. Leave it as default and the directory will automatically be created for you:
iv. The game will install itself automatically afterwards. It will prompt you on whether you would like to create a desktop shortcut. Select 'No'.
Exit the installer. RoC installation has been completed. Now let's move on to...
b) Installing TFT
i. Begin the same way by replacing the RoC disc in the CD drive with the TFT one. Double-click the disk drive icon to bring up the installer again if there's no Autorun:
ii. Once again the installer will ask for your CD-key. This key is different from the RoC one, and it is also found on the jewel case of the TFT CD:
iii. The installer will automatically update the RoC installation:
iv. At the end you will again be prompted whether to place a desktop shortcut or not. Click 'Yes' this time.
Exit the installer. TFT has now been installed and you have a desktop shortcut for it. Well done! You will use TFT to launch into DotA from here on out. You can delete the ROC desktop shortcut if you have it.
What needs to be done next after the game has been installed is to patch it to the latest version. This is very important as current versions of DotA will only work on the latest versions of TFT.
Step 2-1: Updating/Patching via Battle.net
The following instructions are for updating and patching TFT through direct connection to Battle.net. For alternative methods, skip to Step 2-2 instead.
i. The simplest way to update to the latest patch is to connect to Battle.Net (Blizzard's proprietary online matchmaking service) via the game itself.
To do so, load up The Frozen Throne using the desktop shortcut you've just installed. The main menu will look like this:
Note the white numbers on the bottom right corner. This tells you what version of TFT you are running.
ii. Click the Battle.net button. The game will automatically try to connect and check if your current installation is up to date or not. As it is currently not, you will see the game downloading the patch:
iii. The game will quit and commence updating automatically once the download is completed. You will get a black screen and a progress bar on the update, after which you will be shown a message on the outcome of the update and the patch notes once it is done:
iv. The game will load automatically once you have closed the updater. The bottom right corner of the main menu will now display a different number than before. To confirm if you have updated to the correct version click the Battle.net button again. You are successful if the game brings you to the Battle.net account login/registration screen:
Step 2-2: Updating/Patching via manual alternatives
If you are unable to patch your Warcraft III: Frozen Throne using the Battle.net method mentioned above, you can use other alternative methods mentioned here.
Visit:Blizzard Frozen Throne Patches
This site will have the latest update patch for the Warcraft III: Frozen Throne game. Download the file using one of the mirrors.
Example: The current latest patch is 1.24e. Use on of the mirrors and download your patch respectively either for your PC or your Mac.
Once you have your patch downloaded, run it and follow the steps mentioned on the installer to patch your Warcraft III to it's latest version.
Congratulations! You have installed RoC and TFT and patched it to the latest version. Now let's get some DotA!
Step 3: Download DotA onto your computer
You can use the following links to download DotA on your computer.
Latest Version:Get DotA Latest AI Map:DotA AI A detailed guide on playing the AI Map can be found HERE.
Once you have the map downloaded,
you will need to copy the map to your Warcraft III > Maps > Download folder.
Note: You may need to create those folders in your Warcraft III installation directory.
That's it! DotA has been installed and you're now ready to start playing.
Step 4: Launching DotA
a) Playing on Local Area Network (LAN)
1. Start Your Warcraft III
2. Then Click on "Local Area Network"
3. Then Click on "Create Game"
4. Then choose the version you want to play and Double Click.
5. Because you are not connected to an online network, you will have to just set one of the opponent slots to computer (merely a workaround, won't put actual computers yet) and then press "Start Game" to enter the world of DotA.