Lords of the Fallen is an action RPG set in a fantasy universe where no sins are forgotten and the rulers aim to banish all sin from humankind. The protagonist is Harkyn, a criminal who carries his sins as runes on his face. He is convicted for crimes not revealed to the player. The human realm is attacked by an army of gods and Harkyn is released to fight them, as a chance for redemption. The linear story is divided into different acts that guide Harkyn and his mentor through the Rhogar dimensions inhabited by demons. He can form temporary alliances, but needs to travel into the heart of the realm. New areas are opened up by progressing, with the option to revisit earlier locations, and areas often have multiple paths with hidden locations. There are many additional quests, NPCs and a large amount of lore. Saving can only be done at specific glowing gem checkpoint locations, also used to replenish consumable items such as potions and to upgrade the character.
At the start of the game a combat style can be chosen based on three magic types: brawling, deception, and solace, with four specific spells each. They largely translate to melee, rogue and mage classes. Regardless of the magic type three equipment selections are available next: cleric, rogue and warrior, with a specific type of armour, weapon and shield. By defeating enemies experience is gained to unlock new skills and spells to use in combat. Some mechanics are similar to the Dark Souls games as fights are often set in close quarters and heavily focus on strategical use of attack, defense, dodging and spells. The player is also rewarded for taking risks. Also similar is when after dying Harkyn respawns at the latest checkpoint, there is a timer to quickly return to the area where he died to reclaim all unspent experience. Defeated enemies, except for bosses, respawn as well. There are many different types of weapons to discover and runes can be equipped to boost statistics or to craft them enhancing weapons. A multiplier is built up for mixing different types of combo attacks, but also for avoiding checkpoints and saving up experience instead of spending it on skills. As soon as a checkpoint is used, the multiplier is reset. It is however also possible to use a checkpoint without resetting and that way enemies do not respawn, but health potions are not restored either.
During combat it is possible to lock onto opponents. Timing is important to use the shield to block incoming attacks, followed up by a chain attack, or using evasion through ground rolls with temporary invincibility. Combos can be performed by mixing light and heavy attacks with certain risks for attempting chaining as each enemy has different ways to recover. Charge attacks provide more damage during combat. There are three bars at the bottom that can be leveled up: health (red), energy (orange) and magic (blue). Each action drains the energy bar for a certain amount and it takes some time before it is filled up again. By timing well and by performing combos, the use of energy is minimized. There is an inventory where different types of items can be stored or equipped, with a maximum amount of weight. Skills can be upgraded for overall statistics (strength, vitality, faith, endurance, agility and luck) or for any of the three magic types based on spell points and attribute points with separate experience systems. All the lore is also stored in a separate section in the inventory. After completing the game New Game Plus is available where all spells of the second magic type can be unlocked in the skill three, and for the third type in the next playthrough.