Warhammer 40,000: Inquisitor: Martyr

This is an Action RPG from developer NeocoreGames, who also developed the three entries in the Incredible Adventures of Van Helsing series. The game plays somewhat in the style of well-known ARPG titles like Torchlight and Diablo. The game is set in the world of Warhammer: 40,000, where the player chooses one of three characters to play with differing abilities and fighting styles. The characters are dreaded Inquisitors of the Holy Ordos. Missions take place on a series of maps inside space stations, on planet surfaces, and inside large structures. There is something of an open-world style as the player may ignore the main storyline and select different missions around the galaxy map to gain experience and loot.

[From the Steam store page]

Choose one of the multiple classes and take part in brutal combat encounters: embark on a huge variety of missions with your fellow agents and fight through the single-player story campaign set on a haunted fortress-monastery which hides a terrible secret from the past of the Inquisition.

The first Action-RPG set in the grim future of the 41st Millennium takes the genre to its next level: an open-world sandbox game with a persistent universe with a huge variety of missions, tactical, brutal combat encounters in destructible environments and a storyline influenced by the community of players.