Multiplayer on FFR is a compatibility addon available for most engines that allow the player to interact and play against other players with the goal of achieving a better score than the other player. Multiplayer was very common for use in 2006 and started the use of clans over the forum. However, since the FFR Blackout of 2009 and the reboot of FFR in 2010, there has been little, if not no activity in the multiplayer section of the game. This is due to a huge number of people who left FlashFlashRevolution for other games when the site was down.
The first arrival of multiplayer for FlashFlashRevolution can be dated all the way back to August of 2006, where Shashakiro developed an "FFR Multiplayer Guide" to attract people into using the new multiplayer feature. This attracted much attention for clans and unique ways for people to challenge other players, as people could now interact with them VIA the chat room, and play their favorite songs together. With the addition of new engines for FlashFlashRevolution, different multiplayer servers were made, seperate to each engine, until Universal Multiplayer was created, which spanned across all engines, allowing players to play on whichever engine they are most comfortable with.
With the addition to multiplayer, rankings were also added aside from the original site rankings and song rankings. Multiplayer rankings level in the same fashion that many first-person shooter games use a leveling system, where you would start at level 1 and slowly make your way up through further levels by beating other players. Multiplayer levels and experience required for each individual level increase in a convexed manner, requiring more experience than the last.
The graph on the right shows the experience required to get to the next ranking in Multiplayer, as well as how much experience you will lose (based on a multiplier with your raw score compared to the other player's score) as indicated by the leveling factor.
Other engines (such as the Velocity Engine, and the R^3 Engine,) contain different user interfaces for the multiplayer menu, and contain unique options that other multiplayer versions do not have. This can also be used in advantage for which engine you would like to play on for multiplayer, since these options can have drastic effects on the gameplay.
With hard work put in by the creator of the Velocity Engine and the R^3 Engine, Velocity, and bug fixer and coder, arcnmx, on June 19th, 2013, were able to release a cross-engine compatible server for multiplayer for which players can enter through any engine they liked.
Thanks to the introduction of universal multiplayer, it eliminates earlier problems that arose from using different engines, as players commonly describe Legacy Engine as being "too laggy at times" and other engines such as the R^3 Engine to be "very hard to consistently get perfects".