Thanks for trying to help. I did edit ini files, setting different resolutions and setting window mode on or off (assuming "StartupFullscreen" is the value to set to false?)

Edit: I tried on my laptop with i7-5500U, GT 940m, and Intel integrated GPU, with Windows 8.1 and still same issue.

I'm stuck at the splash screen as well.

Windows 10
I5-3570k 4.0Ghz
R9 390 latest drivers
16 Gig DDR3.

Tried compatibility mode (all of them), verifying files, compatibility mode of the "launch Swat4", loading from the client and folder, and did all of this with 2nd monitor unplugged from the HDMI port.

Did you try installing using the installer downloaded from GOG website? Instead of using Galaxy.

This may sound far fetched but I found that there are errors in the game which is installed from Galaxy. I had to use the downloaded EXE installer and then the game works.

Might be something wrong with the install settings or registry or game path when using Galaxy to install. Theres another thread where we had a problem where the sounds are missing and a critical game function not working. Like the game is using the wrong engine or files.

My game only runs once the first time after installing the game and restarting my computer. Subsequent attempts to launch the game after another restart don't work I have to uninstall and then reinstall and then restart for it to work. I've tried various compatibility settings including admin.

Single Monitor, i7 6700, GTX 1070, 16GB RAM. Windows 10.

Any ideas?

Stand alone installer. I'll try a different file path but the fact it works every single time after a fresh install suggests maybe its something to do with the .exe the installer uses compared to whatever .exe im using to launch after or something.

Edit: Trying a simpler path didn't help. I'll try using GOG since the only time my game works is after an install and using the launch button the installer provides.

I tried this, same issue. Splash screen for sierra appears and then just hangs forever.

I have an I7 2600k, not overclocked, and a gtx 970. temperatures usually hover around 50 celsius. 60 under load.
No problems in any other games. Computer seems to keep running when it freezes, audio and video keeps playing.

I installed from the stand-alone installer (though I used Galaxy to download that). The next time I started the Galaxy client it detected the game and added its needed files to it, but the game works for me. I haven't launched it through galaxy, just the start menu shortcuts. My system is an i7 6700K, GTX 970 and Win10 64bit.

A few things to try:
If you're installing to C:\Program Files, don't do that. Install it somewhere else, like C:\SWAT4. The Program Files directory is protected and the game won't be able to write to the config files.

Try launching the game with the -nointro switch to skip the intro videos. Right click the shortcut and add -nointro to the end of the command line.

Although Windows 10 ships with DirectX installed, it's still missing some DX9 components. Download the DirectX 9 redist and install it.

I have tried everything. Same result on desktop i7-5820K, GTX 980 Ti, WIndows 10 and laptop i7-5500U, GT 940m, WIndows 8.1

I installed from standalone installer.
Tried all compatibility modes
Tried running as administrator
Deleted swat4.ini
Modified Swat4. ini 1920x1080, 800x600, 1280x720, windowed mode
Installed to different file locations, different drives
SInce laptop has Optimus, I can run from either integrated Intel GPU or Nvidia and tried both
On desktop removed second LCD
On desktop set Windows Resolution to 1920x1080
disabled anti-virus and all other background apps

Everything is same result. Just hangs.

Unfortunately I'm having the exact same issues as has been reported here. Running on Windows 10 with Geforce 1070 using the latest drivers.

Splash shows up but the game never manifests itself. No sound, picture or anything else to cling to. Kind of like the d3d has problems initiating (even the geforce experience pop up shows up as it does with other games).

Tried meddling with the .inis, trying the expansion's files, the direct-x drivers, system drivers but nothing seems to work.

The process shows up in the task manager but that's all. Swat 4's .log file stays empty.

How about the nointro fix? http://www.gazchap.com/posts/swat4-dual-monitor-fix/

Also some mention from the old days (8 years ago!) where the game gets stuck at splash screen for minutes (2 minutes! and some other threads mention more!) before the game really starts (no solution though):
http://www.gamefaqs.com/boards/920508-swat-4/43143666

Some mentions and solutions on getting stuck at splash screens / blank screens. Don't know how good the information is in there.
http://induktio.net/wiki/Troubleshooting_&_support_forums

I've seen a lot of old threads (8 years back!) where the blank screen is caused by firewall problems, and that the solution is to enable the game to pass through the firewall first. (Although I fail to see the relevance of it in this day.)

Here's an example:
http://www.dslreports.com/forum/r13130265-Swat-4-Black-Screen

EDIT:
Now I remember... the game has in-game streamed ads, espially in TSS where the posters can be replaced by a real ad.
http://induktio.net/wiki/In-game_advertising

Check if your ADBLOCKERS might be affecting it! (Maybe it prevents the game from running because it is trying to contact an ad server?)

Or try the solution in that link!

Disable your antivirus for a second and try launcing again.

I had the exact same problem as you. Win10, GTX 1070, i5 etc.
I disabled BitDefender for 10s and launched the game. Went to menu without a problem.