From the website:
Warhammer 40,000: Armageddon is set during the Second War for Armageddon. In this hex-based, turn-based game developed by Flashback Games and The Lordz Games Studio, players will lead the Imperial forces of the Armageddon Steel Legion and Space Marines from a variety of Chapters against the Ork invasion through over 30 scenarios, on the hostile terrain of the planet and its gigantic Hive Cities. The game features a complex plot, involving known characters from the Warhammer franchise and while advancing through the campaign, the player will have the ability to carryover his core force from scenario to scenario.
Players fight alongside Commissar Yarrik and Commander Dante against the cunning Ork Warboss Ghazghkull Thraka and carry over battle-hardened veterans from scenario to scenario, using their experience and upgrading their equipment.
Also extensive modding options are available through a powerful and easy-to-use game editor.