"Fallout Shelter," the first mobile game in Bethesda's "Fallout" series, has been so successful that more and more iOS users are downloading the app, and even Android mobile device owners are asking when the app will make it to their devices. 

In "Fallout Shelter," players are tasked to build and manage a vault, much like how it is set up in the popular "Fallout" series of titles. There are items and equipment to build, resources to collect, and dwellers to take care of.

Although the game is free to download and play, gamers have the option to purchase paid "lunchboxes" that deliver items and rewards. For those who want to just enjoy the game, there are tricks and handy tips to level up faster without shelling out for paid items. 

Build with a purpose 

One trick to produce more resources is to build a number of the same rooms, and build these particular rooms next to each other, to widen their capacity for dwellers and resources. For example, building three diners adjacent to each other will fill up the food meter much faster. However, players must keep in mind that bigger rooms need more electricity. 

Check dwellers' traits 

Each dweller has a particular trait, and their personalities play in the chosen building they would be assigned. When building, the traits that work best with a particular structure will be shown. Players need to fill up the dwellings with people that would best serve there by checking the green number above the dweller's avatar. 

Upgrade whenever possible 

In "Fallout Shelter," there are enemies called Raiders which break into the vault from time to time and get away with resources. One way to prevent Raiders from ransacking the Vault is for players to collect enough bottlecaps and upgrade the vault door. Another way of preventing attacks is to place armed dwellers in buildings nearest to the vault entrance.