I played the first game back in the 90's, but never tried the second and third one. Now I decided to correct that issue and got the entire trilogy.

In the first game you can choose between Emily Hartwood and Edward Carnby, but in other games you play as Carnby. I don't think that there was a huge difference between the stories, but it's been about 20 years since I last played this game so I can't remeber for certain. In any case I was planning on playing the entire trilogy and I was wondering does it matter continuity wise which character I select i. e. do the later games assume and make references that it was Carnby who defeated the baddies in the Derceto mansion. If they assume that Carnby version is the canonical one then I'll probably play as him.

They do have different introduction story, but that's probably the only difference. I was wondering does AitD3 make any references to the story of the first game, after all Edward is trying to rescue Emily in that game?

Right, forgot about the introduction ;) But I'm fairly sure it is the second only difference after their appearance of course.

I cannot be so sure about AitD 3 because I don't like sequels that much and I finished them only twice. AFAIR AitD3 is not any "alternative plotline" but a straight continuation of the previous parts although they are loosely connected. True, Emily is the damsel in distress here but I think there were no (or very little) other references to the first part of the series.

I believe the 'official' continuity is that Carnby was the survivor of the horror at Derceto

I don't know if it's just me. But Emily definition has the least awkward running animation.

Carnby looks like he has a coin stuck up his ass when he runs.

What happened is that the idea with AITD1 was to have two characters with two different stories and different puzzles. However, the publisher rushed the developers when they only had the Emily bit done (Edward wasn't even properly modeled), so they had to akwardly fit Edward inside Emily's history.

She was there in HER house where she lived as a child to investigate the death of her dear uncle and why he secluded himself. They made Edward, a PI to break in someone's else house to do what could be called rob a piano too big to be moved and some art. Edward just doesn't make sense in there!

In the other hand, they moved from a sophisticated Lovecraft psichological horror history to blooming mafia-pirate zombies action game in 2 and stupid cowboy zombies in the 3 part. 4th was not even in the same time period and Edward had a three barreled shotgun =.=

If history is important to you, play with Emily in AITD 1 and treat AITD 2 and 3 as different games not related with Alone in the Dark in other way than sharing the same engine. AITD 4 is just a Resident Evil clone.