There's this guy who's on another planet. I can't remember why or how, but he's become separated from his companions (and spaceship) and is lost. He becomes convinced that there's some kind of monster on the planet. If I remember correctly, there's a part where he tries to construct a shelter (with logs?) but becomes convinced the monster is nearby and I think he then runs off.
There's two parts I remember the most clearly. The first is that there's a part where he finds his spaceship and is initially really happy about it, but then discovers the spaceship has been there for way too long to have been his, and presumably belonged to some other group that had previously been there but for some reason never left.
The story ends, I believe, with him finding a place that he thinks where the monster lives. He sees what he believes to be the monster. I can't remember what he does in response, but I think he runs away because of it. But the reader discovers that he was looking at his reflection (maybe it was in water). The implication is that he's actually been on the planet for a really long time, but has gone insane and convinced himself that he just got there. The spaceship he found therefore was his own, and the reason he thought his reflection was a monster is because he's been living in the wild for so long his appearance is scary. The story doesn't really come out and spell this out for you, though, you just figure it all out after you discover he was afraid of his reflection.
Anyone know this one?