From the developer's website:
Grim Dawn is an action role-playing game intended for digital distribution on the PC. It is being developed by veterans of Iron Lore entertainment, the makers of Titan Quest. Grim Dawn is being built with Crate's own improved version of the Iron Lore engine and toolset; the same technology used to create Titan Quest. As a spiritual successor, Grim Dawn will attempt to better perfect the magical formula of exploration, character advancement, and loot collection pioneered by Diablo.
Players will be thrust into the dark, war-torn world of Cairn where a once proud empire has been brought to ruin and the human race driven to the edge of extinction. Cairn has become ground zero of an eternal war between two otherworldly powers, one seeking to use human bodies as a resource, the other intent upon destroying the human race before that can happen. This cataclysmic war has not only decimated human civilization but is warping the very fabric of reality and, in its wake, giving life to new horrors.