Announced at PAX East just now, the first Titanfall DLC is called Expedition and will arrive May 2014.  Coming this May, Expedition will introduce three new maps to the Frontier including Runoff, Swamplands and Wargames.

Swamplands features tree running, meaning you can jump between trees, and even run on top of these. The setting for this map is like an alien type base.

In the wake of the Battle of Demeter, IMC Expeditionary Forces travel deep into Frontier space to recover from their recent defeat. On an uncharted world, the IMC begin construction of a new fleet operations base, using newly acquired water collection and filtration plants to support the new base. When drainage operations reveal ancient ruins and artifacts of an unknown origin in a nearby swamp, Spyglass activates an archaeological team to investigate the site. To maintain battle readiness at the new base, IMC Pilots use simulation pods to train for anticipated Militia raids, based on lessons learned in Angel City and IMC Airbase Sierra.

This first DLC is also included with the Season Pass. The Season Pass costs $24.99 for the 3 DLC packs set to come for Titanfall.

SOURCE: Titanfall