In May 2006, the PE-2 (domestically known as Истории пикирующего бомбардировщика, "Stories of a dive bomber") add-on was released in Europe and North America. This added 95 campaigns, five single missions and five multi-player cooperative missions. Two new flyable aircraft, the Petlyakov Pe-2 (four variants) and the Petlyakov Pe-3 (two variants), as well as a large number of new ground vehicles and artillery were also included. When installed, PE-2 is merged with previous games in the series
Source: Wikipedia, "IL-2 Sturmovik (video game series)", available under the CC-BY-SA License.