The first online game, Maze War, was developed in 1973 by Steve Colley and Ken Backe.

Ultima Online, released in 1997, was the first MMOG to gain widespread popularity.

Ultima Online was the first online game to introduce the concept of guilds, allowing players to form groups and work together to achieve common goals.

Netrek, released in 1981, was the first online game to feature PvP combat, allowing players to engage in battles against each other.

World of Warcraft, released in 2004, was the first online game to introduce the concept of microtransactions, allowing players to purchase in-game items and services using real-world money.

Ultima Online, released in 1997, was the first online game to feature a subscription-based business model, requiring players to pay a monthly fee to access the game.

Counter-Strike: Global Offensive, released in 2012, was the first online game to introduce the concept of loot boxes, allowing players to purchase randomized in-game items.

PlayerUnknown's Battlegrounds, released in 2017, was the first online game to feature a battle royale mode, where players compete against each other in a last-man-standing match.

Fortnite, released in 2017, was the first online game to introduce the concept of cross-platform play, allowing players on different platforms to compete against each other.

Half-Life: Alyx, released in 2020, was the first online game to feature a VR mode, allowing players to experience the game in a fully immersive virtual environment.

CryptoKitties, released in 2017, was the first online game to introduce the concept of NFTs, allowing players to collect and trade unique digital cats.

Axie Infinity, released in 2018, was the first online game to feature a P2E model, allowing players to earn cryptocurrency by playing the game.

Second Life, released in 2003, was the first online game to introduce the concept of a metaverse, allowing players to create and interact with their own virtual worlds.

CryptoKitties, released in 2017, was the first online game to feature a blockchain-based economy, allowing players to buy, sell, and trade unique digital cats using cryptocurrency.

Decentraland, released in 2017, was the first online game to introduce the concept of a DAO, allowing players to collectively govern the game's development and decision-making.