Saints Row 2 has a gameplay structure similar to Saints Row. On foot, the player’s character is capable of walking, running, swimming, climbing and jumping, as well as utilising weapons and basic hand-to-hand combat. After Saints Row was produced and work begun on Saints Row 2, the streaming engine was completely rewritten. Because of this, new air-based vehicle types and online co-operative play have been made possible, along with many new major improvements to provide a smooth, interactive world, with significant decreases in terms of glitches, bugs and pop ins. The game incorporates three difficulties: casual, normal and hardcore, which can be changed at the beginning of the game.