Steam players hit "Failed to load steam_api64.dll": the depot that ships the game but not the DLLs the game loads first

verbatim error"Game won't launch" — Failed to load 'steam_api64.dll' (error 126) "Crash on startup" — The code execution cannot proceed because VCRUNTIME140.dll was not found.

Problem

The game works on every dev machine, and the Steam review queue fills up within an hour of release:

"Game won't launch" — Failed to load 'steam_api64.dll' (error 126)
"Crash on startup" — The code execution cannot proceed because VCRUNTIME140.dll was not found.

Running the same build from the shipped folder on a clean test VM reproduces it instantly — the defect was in the depot all along, invisible on machines with dev tools installed.

Root cause

Two distinct DLL failures that look identical to players:

1. steam_api64.dll error 126 (module not found): the Steamworks SDK redistributable was never copied into the depot. Build scripts routinely exclude *.dll from a clean-copy pattern, or the SDK redistributable lives outside the project directory and CI's staging step never sees it. 2. VCRUNTIME140.dll missing: the game was built with the MSVC runtime dynamically linked (/MD), and a player without the Visual C++ Redistributable installed has no copy. Dev machines always have it; a fresh Windows install does not.

Both are invisible locally and both were caught by players, because the depot was assembled by a script nobody ran end-to-end on a clean machine.

fix preview — first 3 of 13 lines (text), truncated:

"DepotBuild"
{
    "DepotID" "48001"
… 10 more lines in the fix

🔒 the fix — including 3 code blocks — is members-only. $1/mo unlocks everything.