The gameplay of Extreme-G primarily revolves around fast-paced racing through a variety of futuristic environments. An assortment of defensive and offensive weapons can be found on the track.[4] These weapons include multi-homing/reverse missiles, magnetic and laser mines, as well as shield-boosting power-ups. Special weapons, such as invisibility, phosphorus flash, and the formidable Wally-Warp, can also be collected; if not avoided, the Wally-Warp can instantly transport a bike to the back of the pack.
As with all Extreme-G games, players control futuristic racing pilots riding plasma-powered bikes in an intergalactic Grand Prix, reaching speeds of over 750 km/h. The focus is on speed and innovative racetrack design, with tracks looping like roller coasters.
At the beginning of each round, players receive three "nitro" power-ups, which provide a temporary speed boost (these power-ups cannot be replenished). Additionally, falling off cliffs or, in some instances, the track itself results in merely losing time rather than lives; bikes are teleported back to the track and must regain their speed and recover lost time from a complete standstill.
The single-player mode offers three difficulty settings: Novice, Intermediate, and Extreme. The main game mode, known as Extreme Contest, features three championships: Atomic (four tracks), Critical Mass (eight tracks), and Meltdown (a full set of 12 standard tracks). Players must secure first place in each championship to progress. Winning championships across various difficulty levels unlocks hidden bikes, levels, and cheats. Once these levels are unlocked, they can be used in additional single-player and multiplayer modes.
The multiplayer modes include competitive racing, flag capture, and battle mode.