Grim Dawn is an action RPG in the Diablo lineage, made by people who worked on Titan Quest, and it is widely considered the best-built game in that genre that is not made by Blizzard.
It is dense, grim, set in a ruined world called Cairn, and it respects your time in ways its competitors often do not.
The dual mastery system
You pick two of nine masteries and combine them. Soldier and Demolitionist. Occultist and Necromancer. Arcanist and Inquisitor.
That single choice creates the character, and you cannot change it. Every pairing is viable, which means the build space is enormous and genuinely open rather than nominally open with three correct answers.
Devotion, the second tree
Shrines across the world grant devotion points, spent on a constellation map with its own affinity requirements. Certain constellations grant abilities you bind to your own skills, which then fire automatically.
It is effectively a second character sheet and it is where a lot of the game's depth sits.
Loot and the endgame
Items, sets, and Monster Infrequents that drop from specific enemies and often beat the advertised sets for a specific build.
Endgame is the Shattered Realm and Crucible, plus Nemesis bosses that spawn once you push a faction's reputation far enough.
What matters most, mechanically
Resistances. They cap at 80%, Elite subtracts 25 and Ultimate subtracts 50, so a character comfortable in Normal walks into Ultimate badly exposed.
Almost every "this game got too hard" complaint traces to resistances rather than damage.
Where it sits
Slower and more deliberate than Diablo, more generous with build freedom than Path of Exile, and considerably less overwhelming than either.
The expansions, Ashes of Malmouth and Forgotten Gods, both add masteries and content and are close to essential.
Time commitment
A campaign playthrough is 30 to 40 hours. Reaching Ultimate and gearing a character properly is well over a hundred.
Factions
Several factions offer reputation, and reputation unlocks augments, which are a large share of your resistances and damage late on.
Two of them, Kymon's Chosen and Death's Vigil, are mutually exclusive. Choose based on which augments your damage type wants rather than on the story, because the augments matter and the story here does not branch much.
Pushing a faction's hostile reputation far enough spawns Nemesis bosses, which are the real endgame test.
Multiplayer and mods
Co-op works and scales enemy difficulty. Nothing is balanced around it, so a duo clears content faster than intended, which is fine.
The mod scene is substantial, and Grimarillion and Dawn of Masteries in particular add masteries from other games. Worth knowing about after a first playthrough rather than before.
Difficulty layers
Normal, Elite and Ultimate are the same campaign replayed with harsher resistance penalties. That is the intended progression rather than optional content, and gear that carried you through Normal will not carry Ultimate.
Plan for three passes through the story. It sounds repetitive and in practice the character changes enough between them that it does not feel that way.
Guides
The beginner's guide covers your first character. The builds guide covers masteries, resistances and devotion, and there are also walkthrough, maps, weapons and tier list pages.
