They came from another world… and They brought hats! How kind of Them.
Invasion is a new, community-created update for Team Fortress 2 that brings a slew of new, space-based items, 4 community-created, Invaded Maps and
a chestburster alien Chester. The update runs through November 5th and you can get an Invasion Community Update Pass to track your scores and grab exclusive Invasion item cases as random drops.
What are you waiting? Go kill some extraterrestrials, and also some Earthlings while you’re at it! But first, watch the announcement trailer:
Source: TF2 Invasion Update Page