In both the PC and PlayStation 2, the game's plot follows a more detailed plot different from the television show's, but more similar to that of the show's in-universe game. All of the games' cutscenes are shown in the style of a comic strip with speech bubbles. A prologue at the start of the game describes Lord Fear escaping from prison in the Sixth Dimension and stealing the Amulet, but is stopped by Ace and the following fight results in the shattering of the Amulet. Both individuals find a single piece of the Amulet and take there fight to the Carnival of Doom. Ace collects the Amulet pieces scattered around the carnival's nightmarish attractions, fighting such villains as Googler, Lady Illusion, Dirty Rat and his own friend Random Virus who suffers from multiple personality disorder and has two personalities, one good and one evil. Ace eventually confronts Lord Fear in the Haunted House, defeating him and his minions before sending them back to prison using the restored Amulet.
The PC and PlayStation 2 games are almost identical, the PlayStation 2 version having better graphics and two bonus levels. The gameplay for each level is to reach the end and collect an Amulet piece to continue the game. There are four distinct worlds, a circus, a funhouse owned by Lady Illusion, a wild west ghost town, and a medieval castle. The final world leads straight into a boss battle against Lord Fear and others. Each world has two or three levels that are unlocked one after the other, the last level ending with a boss battle against a specific antagonist (e.g. Lady Illusion, Googler, Dirty Rat, Random Virus), an Amulet piece appearing after they are defeated using a repeating technique. The Amulet piece at the end of the each level may only be gained after a task is completed, like defeating enemies or a boss, or collecting enough tokens called Doom Dimes.
Most of the game involves platform jumping or locating keys to new areas that appear as actual keys or as large activation buttons. Combat has two stages. First Ace Lightning will fight with a weapon called the Lightning Lance which can fire out lightning bolts or he can use it strike opponents. The lance has an energy bar which will eventually run out and Ace is forced to use his fists and wrist cannons for combat, his cannons capable of stunning an opponent for a period of time. Ace can power up the Lightning Lance by collecting lightning bolt symbols. When enemies are defeated, they leave behind energy balls that can also replenish the lance. Ace can also gain accessories for a period of time, including an energy drink to heal his life bar, the Shield of Justice which protects him with a force field, and an ability to double jump, as he is unable to fly in the games as he is shown to in the television series.
Source: Wikipedia, "Ace Lightning (video game)", available under the CC-BY-SA License.