Dwarf Fortress saves are not stored in a single file. They are stored as named directories containing over a thousand individual data files. In order to load the game, you need to download a zipped archive of the save and place it in your Dwarf Fortress save directory. This directory can be located in a number of places depending on which OS you are using and what settings you have enabled.

If Portable mode is enabled (not default), the save directory will be located in the same directory as dwarfort / dwarfort.exe. If you are using Steam with the default locations, these are:

On Linux: ~/.local/share/Steam/steamapps/common/Dwarf Fortress/save

On Windows: C:\Program Files (x86)\Steam\steamapps\common\Dwarf Fortress\save

This directory might exist, even if Portable mode is turned off (default), but in that case it will be ignored by the game. Instead, save files are stored somewhere in your user directory.

On Linux: ~/.local/share/Bay 12 Games/Dwarf Fortress/save

On Windows: %AppData%\Roaming\Bay 12 Games\Dwarf Fortress\save

Extract the FFSeason1 directory from the archive and place it inside of the appropriate save directory, then you should see it after starting the game.

By using a combination of the "Autosave Frequency" (any setting as long as it is not "Off") and "Pause after every autosave" options, you can cause the game to pause at the exact moment the calendar ticks over to 1st Granite (the first day of the year).

After the game pauses, you still have the opportunity to do a couple minor things, like designating blueprint tiles to label hazards, noteworthy sources of material, or leaving graffiti. You can also rename stockpiles and rooms, etc. before writing the final save. You should avoid doing anything that will substantially change the behavior of the fort or generate labor tasks (like creating / removing stockpiles, changing which items are allowed to be stored in stockpiles, enabling / disabling standing orders, creating new work orders, or designating new rooms / meeting areas). Military schedules often change at the start of a season (e.g. the "staggered training" preset). This is fine.

Any blueprints left are merely suggestions. The next player is free to ignore them. If you wanted something built there, you should have microed your miners better :P

When Dwarf Fortress creates auto-saves, or if you use the "save and continue playing" feature, Dwarf Fortress will write these saves to an alternate directory (e.g. autosave1 or pull the lever). When you finish your turn, you need to use the "Save and return to title menu" option and choose "Save to this timeline." You need to do this even though the game just created an auto-save. This will write the save back to the FFSeason1 directory, which you can then place in a zip archive and submit.

Save files can be e-mailed to fortress-friday@matapacos.dog ahead of time. Some e-mail services (like Gmail) prohibit sending large enough attachments, but if it works on your end, it should work on mine. Otherwise, the file may need to be hosted using a third-party service. Dwarf Fortress File Depot is the canonical service for this (they have a category specifically for community games), but any service which doesn't require me to create an account or jump through flaming hoops is acceptable. Currently, the compressed save is about 50MB. It won't get any smaller with time.

Alternately, submissions can be made as a reply to the following week's Fortress Friday post, which will be posted in anticipation of a submission. This thread will be posted and used to coordinate the game and get the proper files into the hands of the next player regardless of if the anticipated turn was completed.

Whether or not the file was transferred in advance, The player who just completed their turn should make a top-level comment in this thread describing noteworthy events of their turn. You are encouraged (but not required) to roleplay and continue to spin a fantasy narrative out of it, but you don't need to write us a Tolkien novel - especially if you are pressed for time and have other shit to worry about. This shouldn't feel like a homework assignment.

My initial submission will be excessive because I am also covering the results of world-generation, the historical circumstances of the civilization we chose, and the embark. Subsequent posts will mostly be focused on chronicling events in Fortress Mode. You are absolutely not expected to export the world history and spend hours dicking around in Legends Viewer spinning up backstories for every minor goblin who gets turned into dog food.

If you anticipate not being able to complete your turn, just let us know (the sooner, the better) so we can make adjustments. Shit pops up. There are more important things in life than a stupid game. We won't be mad at you.

In case Fortress Friday rolls around and there is no submission, Tentatively, I think we give the player 24 hours to actually make their post before we start openly contemplating passing to the next player, followed by another 24 hours to find out which of the next players is actually available. So if there is no update by mid-Saturday, we find another candidate, and if there is no word by mid-Sunday, they are given the green light to play.

You can tease us (it's reassuring to know progress is being made), but hold on to your spoilers until Fortress Friday. I think keeping this thing on a regular schedule will do a lot to keep everybody looking forward to updates and keeping things organized. If anticipation is eating away at you, try to fill in some lore and backstory.