Assassin's Creed II Unlock Bonus Content

On June 1st, 2021, Ubisoft closed servers of Assassin's Creed II. These servers were activating additional content in your saves. Now that the servers are down, this content, such as Ubisoft Connect rewards or Deluxe Edition bonuses, cannot be unlocked. The only way to access them is to load an old save file that has them activated.

However, after some research, I found a way to unlock this content in new saves. In the following sections, I will describe how to do it. For those who don't want to modify the file themselves, here is a download link to the prepared file:

https://drive.google.com/file/d/1Z3EfolrLk35_bwh4xBFd_h26f_EvM64W/view?usp=sharing

First of all, the save files are located in "C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\savegames\[Ubisoft account ID]\4".

There are two save types in Assassin's Creed II. The first type is responsible for settings and unlocking the content, while the second type contains data about game progress, Ezio's location and your session's name.
Depending on which one is created first, these saves may have different numbers. If you start by changing some settings, the first type will be created and thus it will have number 1. However, if you start a new session without changing anything, the second type will be created first and this one will be number 1.
There are also "files" with .upload extension. These are just indicators pointing which saves should be uploaded to the cloud. They are empty and do exactly the same as adding .upload extension to your save files.

You can identify your save type by size of the file. The second save type is much bigger and grows as you progress through the game. The first save type is around 3 KB and doesn't change much later.

The one that interests us is the first type.

First, you need to create a save file of the first type. You can do this by simply launching the game and turning subtitles on, which are turned off by default. You don't even have to create a new game session.
If you're unlocking content in your current saves, make sure to back them up just in case.

Next, you need to open the save file with a hex editor. I used HxD. Go to "5F2" offset. This is where the values that interest us begin. You need to change "00" values to "01" in the offsets listed below to activate the content.

• Deluxe Edition bonuses:
  
  1. 5F2 - Palazzo Medici Templar Lair
     
  2. 604 - Santa Maria dei Frari Templar Lair
     
  3. 616 - Arsenale di Venezia Templar Lair
     
  4. 63A - Bonus outfit dye
• Ubisoft Connect rewards:
  
  1. 694 - Throwing knives capacity upgrade
     
  2. 6A6 - Altaïr's outfit
     
  3. 6B8 - Auditore Family Crypt
• Bloodlines weapons:
  
  1. 78B - Maria Thorpe's Longsword
     
  2. 78C - Fredrick's Hammer
     
  3. 78D - Mace of the Bull
     
  4. 78E - Dark Oracle's Bone Dagger
     
  5. 78F - Twins' Rapier
     
  6. 790 - Bouchart's Blade

After modifying and saving the file, the content should be unlocked.

If you're using cloud saving, add .upload extension to the file you just modified. Depending on the save number it may be named "1.save.upload" after that. There is probably an indicator file with the same name in this folder already, so just delete it. This will upload your modified save to the cloud and replace the old one. If you wouldn't do that, the old file would keep replacing the new one every time you launch the game.

Now all you have to do is progress enough in the game's plot to access the desired content.

Battle of Forlì and Bonfire of the Vanities sequences are already integrated into the game and do not need to be unlocked. They start by themselves after sequence 11.

So in the end it all comes down to turning zeros into ones. Unfortunately, in next games in the series, the content unlocking system looks different, and I haven't found the time to decrypt it. But at least this game was saved from being stripped of its additional content.