During a period of expansion, the Kryptonian race created many World Engines and used them to colonize many other planets. However, after the discovery of artificial population control, the colonies established were abandoned as they were no longer needed.
Following Krypton's destruction that resulted in their escape from the Phantom Zone, General Zod and his Sword of Rao loyalists searched through the abandoned colonies for other Kryptonians who may have survived the implosion. During this time, while visiting Daxam, the group came across a World Engine and attached it to their starship, the Black Zero.
After a Kryptonian known as Kal-El activated a beacon in the Fortress of Solitude, Zod followed the signal to the planet, Earth, and decided to terraform it in order to help the Kryptonian race flourish once more, even if it meant killing the indigenous lifeforms that lived on it.
Seeking to stop General Zod and to prevent him from carrying this plan out, Kal-El (now known as "Superman") confronted the World Engine, which had been deployed to the Southern Indian Ocean. Despite getting initially swatted around by the machine's metallic tentacle appendages and getting pinned by its gigantic gravitational beam, Superman soon managed to summon enough strength to fly upwards and destroy the World Engine, effectively ending the terraforming process.
18 months after the World Engine's destruction it's huge wreckage could still be seen in the Indian ocean, Lex Luthor had a team of divers explore the underwater area that the Engine was once positioned above, and they ultimately discover that a portion of the seafloor had been terraformed into a large nugget of Kryptonite, a radioactive green xenomineral deadly to all Kryptonians.