Actually, many of you might not even know there was a time before battle net. Let me give you a quick impression of how it was to play Warcraft 2 in what we shall call the "prehistoric" times:
You would wake up very early in the morning (maybe 6am) to make sure nobody in your family would make or receive a phone call. Then you would hook up your 28.8kb or 33.6kb modem to the phone line and let it dial in to the internet. The guy who invented the sound that these modems make when dialing in now probably works for some terrorist organization...
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imagine it so loud that you'd run the risk to wake up family members
Ok, once you made it online you would open your browser and go to a Warcraft 2 Ladder website, then start your IRC client and enter a Warcraft 2 chat room. In this chat room you would ask for anyone interested in playing a ladder game. Once an opponent registered on the ladder was found you would agree on who would host the game and then trade IP addresses.
The hosting player would start up WC2 and host a game while the other player would start up his WC2 and manually enter the IP address to connect to.
Then you would play a game. Remember that if any family member would pick up the phone you would get disconnected.
Once the game finished the winner would manually enter the result in the ladder website and the loser would confirm it. Once a day or once a week (I don't remember) an administrator would create the new ranking based on the entered results.
This is how you played before battle net!