Justice League Heroes: Flash is a handheld spin-off of Justice League Heroes, where you play as The Flash in a game that plays something like Final Fight on speed. An army of robots has invaded Earth, starting with Flash's hometown of Keystone City. Flash must defeat them there as well as other DC Comics' locales such as Metropolis, Gotham City and the Amazon.
Gameplay revolves around walking from left to right, punching and kicking enemies using combo attacks until their life-bar is depleted with an occasional boss-battle. The added twist of Flash's super speed powers allows for instant dashing to the next enemy and slowing down time, although Flash himself still moves normally, allowing him to run around defeating multiple enemies before they can react.
While Flash is the only playable character, other Justice League members do have cameo appearances, such as Black Canary, Superman, Wonder Woman, Martian Manhunter and Green Arrow, who can be summoned for brief assistance in clearing enemies. The game also features additional modes, including a boss rush mode and a making-of minigame where you race against Superman.