First Encounter is the level where you start finding SI.As such this is the first "real" level.You see some of the "basic" special infected and have to kill them to proceed.
Nothing really,just pay attention to the Data Tutorials and follow them.Then the next mission begins.
|Chapter 1||The Beginning / Starting out Fresh / First Encounter / The Tribals / Total Madness!!! / Relief / Assisstance / Ambush! / The "Thing" / Holy Mother of Five Dog!|