The following is a list of all the items which become available when you reach a certain level. Once you reach level 13 and can obtain the Legendary assault rifle ("Warrior Assault Rifle") you will be able to obtain all in-game items (if luck is in your favour).
Nivel 2
Nivel 3
Nivel 4
Nivel 5
Nivel 6
Nivel 7
Nivel 8
Nivel 9
Nivel 10
Nivel 11
Nivel 12
Nivel 13