From the release:
Close Quarters: Infestation allows players to re-create the overrun of the Earth Protectorate research outpost Contego by a previously unknown alien race, the Llysa'ath. This Close Quarters module includes:
New terrain rules, including outdoor terrain such as trees, depressions, bushes, and low walls;
Rules for operating the Llysa'ath, a reptilian peoples with four distinct classes of troopers;
A section on Night Fighting, plus new equipment specifically for use in dark environments;
5 new scenarios depicting the action in and around Contego Base, some of which occur across multi-level scenario maps;
15 pages of new room and corridor tiles rendered at 300dpi, including bonus tiles not used in the enclosed scenarios, and new counters and markers for the Llysa'ath;
Guidelines for converting Close Quarters into a 15mm- or 28mm-based tabletop miniatures game, including tabletop measuring templates and a point-based troop builder to help balance your miniatures-based scenarios.