Spiral Knights is a massively multiplayer online role-playing game created by Three Rings Design and published by Sega. The free-to-play Java-based game was released in 2011,and continues to be updated.

In the game the player controls a knight of the Spiral order which has crash-landed on the mysterious planet Cradle.Knights cooperatively battle monsters throughout the Clockworks the dungeon that fills the planet's interior. They also battle each other in an optional player-versus-player mode.

Spiral Knights reached one million accounts in its first three months and three million accounts in its first thirteen months.The game won Best Online Game Design and was nominated for three other awards in the 2011 Game Developers Choice Online Awards.

The Spiral Knights are a spacefaring army from the planet Isora.Their ship the Skylark has crashed on the planet Cradle. The interior of the planet is filled with a mechanized continually reconfiguring dungeon called the Clockworks. Operating out of the town of Haven on the planet's surface the knights descend into the Clockworks with the goal of understanding the mysterious energy source at the planet's core. They hope to exploit this energy source to resurrect and re-launch the Skylark.

In its gameplay Spiral Knights is a top-down third-person real-time action-adventure game comparable to The Legend of Zelda: Four Swords Adventures.The player controls a single knight and may play solo or with other players. When exploring the Clockworks knights cooperate to defeat crowds of monsters of various types while dodging traps and solving simple puzzles.There are four main bosses each with an alternate "Shadow Lair" variant and numerous mini-bosses. In addition to this player-versus-enemy mode there are two optional player-versus-player modes: one that is similar to Clockworks play and a Bomberman-like mini-game that differs substantially from the rest of the game.

When they are not battling monsters or each other knights train shop trade and chat in Haven. Character progress comes not through the improvement of personal statistics but rather through upgrades to equipment. Weapons include swords handguns and bombs offering various play styles and characteristics.

The game's visual style has been called "adorable" and "cutesy".The art work draws on many traditions and cultures beyond medieval European knights and outer space science fiction— for example cowboys wizards,ninjas,and chefs.

Spiral Knights is massively multiplayer although each player interacts with a small subset of other online players at any given time. Clockworks parties are limited to four knights and player-versus-player contests are limited to six-versus-six. Instances of Haven typically have tens of knights present. Guilds are limited to 100 members by default and friend lists are capped at 250.

The entire game is free-to-play. There is no in-game advertising. Players can spend real-world money to purchase an in-game commodity called energy. Energy can be exchanged for other commodities and currency to accelerate a knight's development. Real money can also buy certain costumes and promotional items.

Sega and Three Rings Design have been faring quite well with their online MMO Spiral Knights since its formal launch in early April.

So well it’s fared in fact that this week Sega marked the one millionth player to join the knight ranks. And to mark the occasion a new area the Ironclaw Munitions Factory is now available for players to explore in Tier 2.

That is just the newest of what’s been some active expansion on the part of developers since launch. That paired with a free to play Steam launch last month and a healthy community to support it Spiral Knights seems a success all around,(Spiral Knights Gold) with Sega’s support at the heart of it all.