That's not it either, since I don't own The Witcher 3 let alone the expansion pass.

Thanks to everyone who has tried to help so far!

I know this will sound stupid but... have you tried sorting by "purchase date" and checking the most recent additions? Or checking the "Orders history" for the same thing?

Thanks for the suggestion, but I already have my games sorted by purchase date. That's why I'm so sure that something has changed, actually. I recently hit a milestone for the amount of games in my library when I bought the recently added Bethesda games. I've bought four games since that milestone, but according to the number of games in my library there have been five items added since then. When sorted by purchase date, there are still just four games newer than the Bethesda ones.

What about gifted or traded games? Those get sorted by the original purchase date of the gift code, not the date you added it to your account. Did you get any like that lately?

Have you accounted for the gifts (Arena and Daggerfall) you get when buying any Bethesda games?

I wish I could!

As for the idea of gifts, nope, I haven't received any gifts, nor have I traded any games. Arena and Daggerfall are also accounted for. This change happened sometime today.

Maybe something to do with The Vanishing of Ethan Carter Redux? I'm running out of ideas... :/

It's not that either, sorry. Does anyone here know if Blitzkrieg: Burning Horizon - Rolling Thunder - Iron Division had its own library item before today? I'm looking through every item in my library and I don't remember seeing the art for it before.

Yes, it was unbundled months ago.

This is genuinely bizarre.

Perhaps you may want to export you library to the GOG wiki to have more eyes inspect it...

Anyhow, to assist you, here is my library, which didn't get any mysterious additions today, so anything you see there is probably not it.

From MaGog's logs for 16 September:

NOTE! CHANGED Witcher 3 Wild Hunt, The, num_unbundles: 2 ***TO*** 3

I find it weird that TW3 already has three boxes on some owners' shelves (two still empty): Game, Expansion Pass, and First DLC. I wonder what will be in the expansion pass box that will not be in the DLC boxes. And I believe this is the only game to have a separate box for a DLC. My guess is that this is in order to allow people who don't have the game on GOG to still buy the DLC here.

Or perhaps (shudder...) this is the first step of another unbundling scheme, whereby each DLC of each game gets its own box.

First of all, thank you very much for sharing that list with me.

I manually went through and compared every game, and I made a list of the ones that were in my library that weren't in yours. The list is as follows:

Battlespire
Black Mirror 3
Crypt of the Necrodancer
DOOM II + Master Levels
Redguard
Morrowind
Arena
Daggerfall
Fallout
Fallout 2
Fallout Tactics
Final DOOM
Hand of Fate
Her Story
Kerbal Space Program
Oceanhorn
OlliOlli2
Saints Row 2
Sea Dogs
Shovel Knight
Sokobond
The Escapists
The Last Tinker
Tropico 4
The Ultimate DOOM
Victor Vran
Ziggurat

Unfortunately, not a single one of those games would make any sense for this mystery addition. I also did not notice any duplicates or anything else strange in my library when I went through the games. At this point, I don't think there's anything else we can do to figure this out.

The theory I'm going with now is that at some point a game was missing from my library without me knowing, and it must have reappeared when Support gave me my refund today. That's the only explanation I can think of at this point.

Thank you again to everyone who has helped with this! I'm sorry we weren't able to reach a more satisfying conclusion.

Train Fever was updated.

Patch 6219 (17.09.2015)
Fixed missing cargo load icons in line vehicle auto replacement tab
Fixed crash caused by mods which added stations without lanes for persons
Fixed stake car invalid mesh transformation (stake_car_1952.mdl)
Fixed main menu hover sound effects
Fixed misaligned rods / linkage animation
Fixed bug causing the game to not recognizing alternative main connection routes
Added new way to specify vehicle load configurations (multiple cargo types)
Improved Norwegian translation

Patch 6181 (17.09.2015)
Added diamond crossover (build over existing crossovers)
Added user interface windows blink / focus functionality
Added create line button to line chooser (as a shortcut for line creation)
Added vehicle cargo load refit feature (vehicles can be refit on purchase and in depots)
Added “forever” animation (a loop animation which can be added to every model)
Added open-vehicle-window-on-purchase setting to main menu
Added “maxIndustryProduction” parameter to game config (base_config.lua)
Added “townGrowthFactor” variable to game config
Added “townSizeFactor” variable to game config world
Added "Not possible - please build track over street" street builder warning
Added alternative “items” format to specify vehicle load levels (see rungenwagen_1890.mdl)
Added padding around window title bar buttons (locate/edit/close) to make better clickable
Added "blend" flag to material AlphaTest
Improved vehicle navigation (instant vehicle reverse, go to depot and set line)
Improved general window positioning (heuristic to avoid overlapping windows)
Improved terrain modify tool (render circle)
Improved electrification/high-speed tools (draw existing tracks red/green, ignore vehicles)
Improved depot user interface (icons instead of text buttons, disabled set line when empty)
Improved vehicle store (added filters, open a window for the first purchased vehicle only)
Improved user interface window alignment (avoid jumping buttons etc.)
Improved parallel track construction (better following and loss collisions now)
Improved track builder bridge/water detection
Improved line pathfinding (allow empty stations)
Improved model file error handling (print missing model files list on load to stdout.txt)
Improved new-vehicle-available notification (show only one message for multiple vehicles)
Fixed ghost vehicle bug (reversing stopped vehicles made them invisible)
Fixed a track builder bug (allow connecting to the "back end" of a switch or crossover)
Fixed track builder slope-too-high problems
Fixed various additional track builder bugs
Fixed a bug which prevented the player from building long tunnels / bridges
Fixed a crash which occurred when mods defined narrow transport lanes
Fixed street materials: made paving/sidewalk reflective (was transparent) and with alpha test
Fixed steam tram engine type (dampftram.mdl)
Fixed vehicle store "year to" calculation for multiple units
Fixed vehicle list/store display of reversed vehicles in multiple units