Regreso al Edén (Return to Eden)

A long and complex space opera with superb multimedia and some of the best action sequences I've seen in IF (non-Spanish speakers can type "fuera" at the first prompt to see the game's prologue). The story of two empires scheming to control an ancient alien technology moves between worlds, shifting alliances and different PC points of view. You can die a lot -- much of the game is spent escaping one Indiana-Jones-style deathtrap after another -- but the puzzles are clever, varied and fair, and there are smart location-sensitive hints (type "pista"). Sophisticated, fast-paced, groundbreaking.