Peeferin

Guys just so you know, the issue has been worled around for a couple of days now. Just use the latest patch available on Fallout 3 Nexus. It reverts the executable to the older version, removes Games For Windows Live and adds essential performance/optimisation stuff. https://www.nexusmods.com/fallout3/mods/24913

Yup ! Same here. That's good news for the modding community. And also Vortex detects the game correctly now, it's been updated super fast, big props to the people managing it ^^

Yeah honestly I might just get another copy of the game on GOG if I ever feel like getting more mods or something. Right now the fix I found lets me play my modded saves and that's all I wanted, hopefully Vortex will get updated to recognize the new libraries and then everything will be solved since you basically only need the old executable and to remove one file to get FOSE to work normally (At least it worked for me). I'm a bit of a beginner when it comes to modding and Vortex made it a whole lot easier for me so I'd be pretty sad if it was doomed to stay that way

UPDATE : I got an older version of the Fallout3.exe file and put it into the directory containing FOSE, then added every other game file of the reinstalled game (on another drive to save my modded directory), removed live.dll and it FREAKING WORKS ! I really didn't expect it to since what I did was basically making a frankeinstein game directory but holy damn it works, I've got the game running using FOSE and all of my mods are there and working. Vortex still doesn't recognise the game sadly so that means installing new mods or even removing any will not be that easy but at least it's a way to not lose modded saves forever ^^ If anyone wants help doing the same don't hesitate to DM me and I'll try to guide you throughout the process, but if you have made the update and uninstalled the game BE CAREFUL to reinstall it in another drive/steam library as to not override your FOSE and mod files, or at least make a copy of the folder beforehand. Idk if it would actually delete them but better be safe than sorry haha

So basically the steam versions of Fallout 3 and Fallout 3 GOTY just got updated to remove GFWL from the files entirely. It's great ! Except now FOSE doesn't work anymore since the files are changed and Vortex doesn't even detect the game anymore (even by setting the game location manually). So basically it's rendered playing modded saves impossible, and of course there's no option to reverse the update at all. I still have my mod library and saves backed up, but I have no idea how to actually get Fallout 3 with mods to run anymore. I heavily doubt that FOSE will be updated considering how old it is, so I honestly don't know what to do to be able to play my modded saves and it's pretty sad. I'm guessing a lot of people are in the same situation too. I'll try reinstalling the game completely and swapping the new executable with the old one to see if that works at all. But honestly if anyone has ideas on how to work around the update or news about new patches or updates for FOSE feel free to post them on this thread. I'm sure a lot of you will know more than I do, I just wanted to get the topic started since it has a huge impact on the entire Fallout 3 modding community