Idle Luca aims to be an easy and convenient RPG game. Users can grow their mercenaries (Velius) by collecting attractive characters. And the progressed Velius collects progression materials even when offline, allowing the users to progress their Velius with ease and continue their adventures when they reconnect to the game.

A huge explosion occurred in the universe where only Ethers existed. The explosion created four attributes (fire, water, wind, and earth), and the by-products of the explosion gathered to create a world later called "Rovelius". Later in the world, the Ethers with the 4 attributes fused to create a god, so his name was Peren. Peren created two children, Urkeith and Omerta, modeled after himself for the new prosperity of Rovelius. Urkeith created darkness and Omerta created light to bring prosperity in their own ways. Rovelius was divided and ruled by the two gods, and each has developed in its own way. Under the protection of the two gods, Rovels gathered together to form villages called Velius, and the world with these villages became called Rovelius. However, the difference between the values of the two gods in the villages caused conflicts, and these small conflicts led to a big war.