Spelunky

Spelunky is the HD remake of Derek Yu's original freeware platformer and the game that codified what later became called the roguelite-platformer subgenre. The caves are procedurally generated and fully destructible, the verbs are fixed — run, jump, throw, climb, bomb — and the depth of the game comes entirely from the interactions between those verbs and a deeply interconnected systemic world.

Monsters, traps, shopkeepers, damsels, and treasure all live in the same physics simulation, which means almost any combination of inputs leads somewhere. You can rob shopkeepers, but they'll hunt you for the rest of the run. You can rescue damsels for health, or carry them through traps and lose both. You can bomb your way through walls, or accidentally destroy the only platform you needed to escape.

Local co-op for up to four players turns the precision platformer into chaos. Deathmatch unlocks 72 arenas for arena combat. The Daily Challenge generates a fresh seed every 24 hours and gives every player on Steam exactly one attempt to compete on the same map. The journal fills out as you discover new enemies, items, and tile types, building toward the kind of mastery that makes the City of Gold reachable.