Hell has frozen over. The forces of Heaven are closing in, trying to extinguish the last flame of the underworld forever. The only hope is a train carrying the Pyre — the sacred flame of Hell — back to its home. The player must protect it across a gauntlet of angelic assaults, floor by floor, card by card.

Monster Train is a roguelike deckbuilder with a structural twist that sets it apart from Slay the Spire and its peers: combat is vertical. The train has three floors, and enemies board from the bottom and fight their way up. The player places unit cards on each floor to form defensive lines, support cards to buff them, and spell cards to intervene at critical moments. Two clans are chosen at the start of each run and combined, creating a mashup of abilities and synergies that defines the run's identity. Five clans and their intersections produce a vast space of possible builds. The covenant system stacks escalating challenge modifiers for veteran players. A competitive multiplayer mode pits players' best daily runs against each other on leaderboards. The Last Divinity DLC adds a sixth clan, new champion encounters and endless challenge modes.

Key Features: • Vertical three-floor combat: place units on each floor to hold the line against ascending enemies • Dual-clan system: combine two of five clans per run for unique synergy builds • Covenant difficulty system with stacking challenge modifiers • Competitive daily run leaderboards - The Last Divinity DLC: sixth clan + endless mode