The very first teaser/trailer showing in what location AC2 will be set.
The first real trailer
The second trailer, this time a gameplay (from in-game shots) one:
A trailer shown on Tokyo Game Show (TGS)
The teaser of Lineage short movies
The intro of the first part of Lineage series (i.e. the first 1 minute of the part #1 ;-)).
Below unofficial trailers spotlighted by Ubi.
Neomatt/Dark Echo's:
A gameplay trailer modified:
The first trailer modified:
