The fan community has reverse-engineered the Flash game to create an online networking layer. This is unstable and requires both players to have the exact same file structure, but it exists for the hardcore purist.
Because the original game only supports single-player natively, you must use tools that "stream" your game to a friend: Binding Of Isaac Wrath Of The Lamb Online -
If you started your Binding of Isaac journey with Rebirth or Repentance , you might look at the title Wrath of the Lamb and think, “That’s the old Flash game, right?” The fan community has reverse-engineered the Flash game
If your primary goal is a smooth online experience, the community generally recommends moving to the The Binding of Isaac: Rebirth The Binding of Isaac: Wrath of the Lamb Steam Gift G2A
If you are looking to purchase these versions, they are available on platforms like and various digital retailers. The Binding of Isaac: Wrath of the Lamb Steam Gift G2A.com ₹270.81 (varies) The Binding of Isaac + Wrath of the Lamb (Digital Key) Driffle Binding of Isaac: Wrath of the Lamb (DLC) Play-Asia.com
Technically, the easiest legal way to play Wrath of the Lamb "online" is via Steam. While the gameplay is offline, Steam requires a connection to download and authenticate.