Flat, Side-View
The flat, side-view is the traditional two-dimensional "side view" of the action, a perspective that has become less and less popular over the years as 3D became the norm. This view was popularized with the once-common "side-scroller" or "platform" games in the late 1980s and early 1990s, such as a few Mario Brothers and Sonic the Hedgehog games.
Some current games still use this perspective, and it may prove to be a refreshing change from all the first-person and third-person perspective games these days. Examples include Titus' Worms series, ARUSH Entertainment's Duke Nukem: Manhattan Project, and the first two Oddworld titles from Oddworld Inhabitants.