Longest series you've played

For me:

All 15 (so far) Haunted Hotel games
11 out of 12 (so far) Puppet Show games
All 11 (so far) Fear For Sale games
10 out of 11 (so far) Dark Tales: Edgar Allen Poe games

I'll get to the 2 I'm missing eventually. Currently playing Grim Facade #9.

Ha! My list would be pretty much the same as yours, Guybrush.

Great topic! Sort of cuts to the chase, and says a lot about the quality of certain series and game developers. I don't think I ever have played ALL the games in a given series. Some were too easy or too "dark" or simply didn't appeal to me. A few crashed or wouldn't run properly or cut off the screen or some other nonsense. For that reason, I always play the Demo first, even if I have enjoyed other games in a series.

In alphabetical order, not order of preference:

Dark Parables: 12 games. These are quite good, but every one is like all the rest, so you have to space them out or the repetitiveness gets to you.
Lost Lands: All 5 games issued so far (that I know of, at least). Most reliably excellent series!
Mystery Case Files: 12 This series has a few stinkers in it, but overall, a good record. (I got hooked into this series with the Ravenhurst ones.)
Mystery Trackers: Played only 9 of the 12 I've seen offered (Some were too predictable, too easy, got too repetitive.)
Nevertales: Played the 6 I've seen. Almost every one a gem!
Phantasmat: Played 9 of the 12 I've seen. Long series, with a few gems as well as a few losers. (Half were so-so, so I am kind of "off" this series at the moment.)
Sable Maze: Played 7 of them,not all. This series can be uneven. (Some favorites, some buggy or too easy.)
Shiver: Only four games I know of but ALL were terrific.
Surface: Another good series. Of the 11 I know about, I've played 8. Some weren't great, but others got my highest rating.

It isn't the longest series, but I agree with Reenie that the Lost Lands series is the most reliably excellent of them all - and all of their other games have been very good, as well.

My longest series so far has been :

Haunted Hotel
Myths of the World
and
Amaranthine Voyage

[I haven't played any of the Lost Lands. I might have to take a look at those ]

EDIT :

Just looked at my Big Fish purchase history and found I've played THREE of the Lost Lands games !!
Just shows how good my memory is

Here is the list of Lost Lands games, from earliest to newest:

Lost Lands: Dark Overlord
Lost Lands: The Four Horsemen
Lost Lands: The Golden Curse
Lost Lands: The Wanderer
Lost Lands: Ice Spell

All are available as Collector's Editions and Standard Editions.

Thank you for that info Our posts crossed, Marian !!

Yes, I see, Mad.

Have a good day.