Spelunky

Spelunky looks like a classic adventure about a treasure hunter in caves, but it's actually a precisely designed game in which every run is generated anew and death means a complete return to the start. You control an explorer equipped with a whip, bombs, and ropes, descending ever deeper while trying to gather as much gold as possible, rescue trapped dogs, and survive encounters with snakes, bats, spiders, and much nastier denizens of the underground. A full run takes only a few dozen minutes at a good pace, but it takes a long time before you're capable of that pace.

The game's strength lies in how honestly all its elements interact with each other. A bomb meant to clear a path can wake a shopkeeper, whose wrath then follows you through the rest of the run. Enemies kill each other, a trap snaps shut on someone other than you, and random confluences of events create stories players still tell to this day. None of it is unfair, because the rules are simple and consistent; the hard part is only keeping a cool head. Progress isn't measured by unlocked gear but by what you've learned, and the game also holds a surprisingly large amount of content in reserve for those who get further than it looks possible at first glance.

The original version began as a freely distributed game with simple graphics; the reworked PC release brought a hand-drawn look, smooth animation, local multiplayer co-op, and an arena mode. Technically it's an undemanding title that runs on anything and loads a new run in an instant. The music is playful and adventurous, creating a sharp contrast with how often you die. Spelunky is often credited as one of the titles that kicked off the modern wave of roguelike games, and its influence is visible in dozens of later projects. Today it still stands as a model of clean, honest design. Anyone who gets past the first caves discovers the game is only just getting started, and the deeper levels offer entirely different environments, enemies, and rules.