The Desert is the first world of the game. It contains 3 areas- 1-1, 1-2, and 1-3. On 1-3, the first boss of the game, Big Bandit, appears as another enemy to fight during the level. This is generally considered the easiest level of the game until you start doing loops. The desert mostly contains large open areas. However, there are some corridors leading off, usually ending in chests or radiation canisters. After completing The Desert, you move on to The Sewers.
A Proto Statue will spawn in 1-2 after looping at least once.