Game install, update and launch problems

Short answer

A download that stops part-way is nearly always disk space, a security tool scanning the file as it is written, or an unstable link. An installer that closes without a message is usually a permissions problem. An update that never finishes is a file failing its integrity check and being fetched again. A client that closes immediately is a missing runtime, a graphics driver, an overlay, or an operating system the client does not support. Read the launcher log before you do anything else: it names the stage that failed.

Three stages, three sets of causes

A desktop game reaches a playable state through three separate stages, and treating them as one is why so much troubleshooting goes in circles. The download writes compressed packages to disk. The installation unpacks and verifies them, writes to a program directory and registers components the game depends on. The first launch loads those components, initialises a graphics device, and opens a connection to the publisher's servers.

Each stage fails for reasons the others do not share. Disk space and network stability belong to the first. File permissions and security software belong to the second. Graphics drivers, runtime libraries and operating system support belong to the third. Before changing anything, decide which stage you are actually in — the answer is visible in what the progress indicator was doing when it stopped.

The download stalls, restarts, or never completes

Symptom

Progress reaches a percentage and stops, or falls back and starts again. The launcher may report a network error, or nothing at all.

Most likely cause: Not enough free space. A large client needs room for the compressed download and the unpacked installation at the same time, which can be roughly double the advertised size, plus temporary space on the system drive even when you install elsewhere.
Also common: Real-time antivirus scanning each package as it is written, which can slow writes enough for the launcher to time out; an intermittent Wi-Fi link; a data allowance that has been reached and shaped by the internet provider; or a mobile hotspot that throttles large transfers.

Check free space on both drives. The drive you are installing to, and the system drive that holds the temporary directory. Leave a comfortable margin rather than the exact figure the launcher quotes.
Pause anything else using the connection. Another large download, a cloud backup or a console updating in the background will take bandwidth the launcher then interprets as a failing link.
Move to a cable if you can. A stalled download on Wi-Fi that completes over Ethernet was a signal problem, not a server problem. If a cable is not possible, move closer to the access point and try again before changing settings.
Let the launcher resume rather than starting over. Most launchers keep partial data and continue. Deleting the partial download forces the whole transfer again and discards the evidence of where it failed.
If it fails at the same percentage every time, the problem is a specific file rather than the connection. Use the launcher's repair or verify function, which re-fetches only the failing package.

The installer opens and closes with no message

Silent exits are almost always a permission or policy decision made by the operating system, and they are silent because the installer never got far enough to draw a window.

On Windows: run the installer as an administrator; install to a path you own rather than a restricted system directory; and check whether a school, workplace or family-managed machine blocks unapproved software. On a managed device the block is deliberate and no local change will bypass it — nor should you attempt to.
On macOS: an application downloaded outside the App Store may be stopped on first open. The supported route is to open it from the Finder and confirm the prompt, then check Privacy & Security in System Settings, where the block is listed with an option to allow it. Apple documents this process in its own Mac User Guide.
Either platform: a security suite may quarantine an installer without a visible alert. Its quarantine log will say so. Restore the file only if you downloaded it from the publisher, and never disable protection permanently to force an installation through.

The update runs forever

A patch loop looks like progress but never ends: the launcher downloads, verifies, fails, and downloads again. The verification step is the important part. Patches are checked against a known value, and a file that does not match is discarded, which is correct behaviour protecting you from a corrupted or tampered client.

Run the launcher's integrity check. It is usually in the settings or game menu of the launcher and described as verify, repair or check files. Allow it to finish; on a large client it can take a long time.
Check the system clock. A clock that is wrong by hours can break the secure connection used to fetch patches. Set date and time to update automatically and confirm the time zone is the one you are actually in.
Exclude the game directory from real-time scanning if your security software supports a folder exclusion, and only for the folder the publisher's client uses. This prevents a scanner from locking a file mid-write and causing the same package to fail repeatedly.
Look at the disk itself. Repeated verification failures at different files, rather than the same one, can indicate a drive developing errors. Both Windows and macOS include disk checking tools, and a drive that reports errors is a hardware matter rather than a game one.

What to be wary of at this point

Searches for installer errors surface a category of software promising to fix drivers, registries or game files automatically. Some of it is merely useless; some of it installs additional software and asks for payment to undo a problem it reported itself. The advice that works is dull and free: use the publisher's own repair function, and the operating system's own tools. If you are offered a download that claims to have detected a fault on your computer, treat it the way Scamwatch describes threat-based approaches and leave the page.

The game closes immediately, or shows a black screen

A client that reaches the desktop and then disappears has usually failed while setting up its graphics device or loading a component it expects to find on the system.

Instant exit with no error

Check first: Graphics driver. Install the current driver from the graphics hardware manufacturer, not from a third-party updater. On macOS the graphics driver ships with the operating system, so the equivalent step is applying pending system updates.
Then: Overlays. Recording tools, chat overlays, hardware monitors and streaming software inject themselves into the game process and are a frequent cause of instant exits. Close them all, launch again, then reintroduce them one at a time.
Then: Runtime components. Windows games commonly require redistributable runtime packages that the installer normally adds. A failed installation can skip them; reinstalling the client restores them.
Finally: Platform support. If the client does not support your operating system, none of the above will help. The platform support page explains how to check this properly.

A black screen with working audio is a different fault: the game is running, but drawing to a display mode your monitor is not showing. Try windowed mode if the launcher offers a startup option, disconnect a second monitor, or set the game's resolution to match the desktop before launching. Where a game writes its settings to a configuration file, editing that file to a safe resolution is often faster than fighting a screen you cannot see.

Read the log, then search

Launchers and game clients write plain text logs, normally in the installation directory or in the user profile's application data folder. Open the most recent file and read the last twenty lines. You are looking for a file path, a port number, a permission denial or a code — something specific enough that searching for it returns the actual problem rather than a thousand general threads.

This is also what a support team will ask for. Sending the log with the first message usually removes an entire round of correspondence.

A clean reinstall, done properly

Note what you would lose. Progress and purchases are held on the publisher's account, not on your computer, but local settings, key bindings and screenshots generally are not. Copy them somewhere first if they matter to you.
Uninstall through the operating system, using Installed apps on Windows or by removing the application on macOS, rather than deleting the folder.
Remove what the uninstaller leaves. A leftover game directory or a settings folder in the user profile can carry the original fault into the new installation.
Restart the computer before installing again, so that files locked by a running process are released.
Install from the publisher's own download and let it finish completely before the first launch.

If you do open a support ticket

Operating system and version, and whether it is fully updated.
Graphics hardware and driver version.
Exactly which stage failed: download, install, update or launch.
The error text, copied rather than described.
The relevant log file, attached.
What you have already tried, so nobody repeats it.

The game will not install, update or start