The "Sonic" series is characterized by speed-based platforming gameplay. Controlling the player character, the player navigates a series of levels at high speeds while jumping between platforms, fighting enemies and bosses, and avoiding obstacles. The series contains both 2D and 3D games. 2D entries generally feature simple, pinball-like gameplay—with jumping and attacking controlled by a single button—and branching level paths that require memorization to maintain speed. Meanwhile, 3D entries tend to be more linear in design, feature various level objectives, different movesets, and allow players to upgrade and customize the playable character. Games since "Sonic Unleashed" have blended 2D and 3D gameplay, with the camera shifting between side-scrolling and third-person perspectives.