The storyline of Save the Earth takes place two years after Godzilla: Destroy All Monsters Melee. The story involves mankind getting hold of Godzilla's DNA, known in the game as "G-Cells." The Vortaak learn of this, once again returning to Earth, controlling a vast army of monsters, including their ultimate weapon: SpaceGodzilla. The player faces down many controlled monsters in different locations. In the climax cut-scene, Godzilla confronts SpaceGodzilla in a final duel. Godzilla blasts off SpaceGodzilla's shoulder crystals causing a black hole to form. SpaceGodzilla is sucked in and apparently killed, forcing the Vortaak to retreat while Godzilla lets out a roar of victory having saved Earth yet again. This time around, new monsters are added as well as more detailed arenas including hills, elevated highways, and waist-deep water. Another addition is Challenge Mode, in which the player must attain goals other than simply defeating their opponent. Also for Xbox there was an online play. This mode is now offline.
Critical reaction to Godzilla: Save the Earth was mixed. GameRankings and Metacritic gave it a score of 61.92% and 62 out of 100 for the PlayStation 2 version, and 64.01% and 63 out of 100 for the Xbox version.
1UP gave the game a "B−" score, saying: "Godzilla: Save the Earth is a fun game and a worthy sequel to Godzilla: Destroy All Monsters Melee. If it had been afforded a little more finesse (especially regarding the Challenges) and a little more authentic Godzilla flavor, it'd be even sweeter. The fact is, though, that unless you're a Godzilla fan, there are better games of this general type out there (War of the Monsters and Def Jam: Fight for New York come to mind). Still, the kaiju in Godzilla's universe are way cooler than grown, sweaty men in tights."