Demon Dungeons is a turn-based tactics RPG with roguelike and TCG elements.
Main gameplay unfolds in enclosed dungeons (each one made of 7x9 tiles).
Player's main objective is to vanquish every foe inside the dungeon.
All actions during combat are taken in turn-based mode. Player has a limited pool of action points to spend each round. Those action points can be spent on movement and variety of actions. Player's actions consist of randomized cards, taken from the player-made deck. Player's deck can bring only 10 cards out of all that he previously unlocked, and (depending on the card's rarity) may take 1 to 4 of the same card. During combat, the player is dealt 4 random cards from his deck that he can use, with each spent card returning to the deck's pool before being replaced by another random card.
Players can use a wide tactical variety of card combinations to suit any preferred playstyles.

Examples of tactics:
Melee combat:
- If you prefer to hack and slash your enemies up-close and personal - you can use cards with piercing attacks or round cleaves, or find cards like “Earthquake” and the legendary and one of the mightiest cards “Titans' Wrath”
Ranged combat:
- Those who find kiting and smiting your foes from afar more to their liking can use cards like “Magic arrow”, “Fireball” and “Lightning spear”
Space control:
- Those who enjoy placing traps, impede enemy movement and control the battlefield can do so with the help of cards like “Mine”, ”Bomb”, “Stun” and “Taunt”

You can also add many supporting cards to your deck, like “Shield” that helps you endure incoming harm for a round, or “Concentration” that adds more action points to the next turn, or even “Prayer” that enhances the attack of all the player's cards for a turn. One could find the unique “Blink” card extremely helpful, since it can teleport the player away depending on its level of upgrade.

Depending on the enemies the player can face - you might want to change your tactics! Foes like skeleton priests are best slain swiftly or from afar- for otherwise they may scatter around the dungeon and summon more allies to aid them. Mighty berserkers can pose a threat both head-on and in spite of the cover player sought out - which calls for more control and wariness from their opponents. Some ghoul enemies can be immune to stun, or resist physical damage, while demonic foes shrug off damage from fire-based attacks.