The plot is not important, but it does exist. Sam travels through different periods of time to pursue Mental and his endless horde of enemies. There is something in the crystals, and sometimes there are dialogues, but it is meant to give the player additional motivation to continue progressing from level to level throughout the four to five-hour campaign.
The campaign can be played in local multiplayer mode, and both characters can use the same weapon racks, although they share the same pool of ammunition. It is allowed to stack up to six units of weapons on top of each other and fire with a single pull of the trigger. A connecting hand is required to combine them, which is often found in secret areas.
Sam’s quest will take him to Ancient Egypt, New Scotland (in the Jurassic era), and then to Pompeii, where he will wage a total war against Maxilla himself. After completing the main game, an additional mode becomes available, allowing players to play with friends online and also create a cooperative campaign.