The only thing missing from Alan Edwardes' Half-Life 2 mod Estranged is a cryptic introduction narrated by Rod Serling, possibly with a door flying into your face from a starry sky. But Estranged's "key of imagination" still unlocks plenty of mystery involving a wrecked ship, a puzzling island, its eccentric inhabitants, and a moonlit beach.

Estranged falls under the mod motif of eschewing explanation for exploration. The hows and whys of your predicament aren't immediately apparent—like any good story, Estranged unravels the truth slowly and subtly until the final twist. You'll solve puzzles and bump into the occasional zombie, but the focus clearly revolves around unfogging what's really going on. Story-driven, atmospheric content is a great way to showcase hard, thoughtful work, and Estranged's tiny touches—the flotsam lining the shore or an island inhabitant's scrounged baubles displayed on a shelf—reflect Edwardes' superb attention to detail.

Edwardes recently released the latest alpha version of Estranged, which you can download on its official website .