See:
http://www.gog.com/forum/baldurs_gate_series/baldurs_gate_on_windows_10_with_nvidia_560_ti On my Windows 10 installation, on a bog-standard desktop computer (Intel CPU, nVidia graphics card), Baldur's Gate 1 and Icewind Dale 1 run without any compatibility settings or patches. I actually needed to remove the DDRAWFIX compatibility patch that GOG installs by default.
The version of Icewind Dale 1 GOG sells is the most complete one, with all expansions. This one has had the Baldur's Gate 2 engine backported to it, and it runs fine. Therefore I expect BG2 (and IWD2) to run fine as well. The most troublesome game in Windows Vista and 7 was Planescape Torment, which needed a some compatibility fixes using the Microsoft Application Compatibility toolkit, even when using the latest GOG version. I have not yet tried this game on Windows 10, but I'll install it tomorrow and see.
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edit: I have tested PS:T, which was the most problematic of the IE games under Windows Vista and 7. It even crashed when closing it, and it needed a raft of fixes in the mentioned Application Compatibility Toolkit. (ACTK). For completeness, I list here what I was using on Windows 7.
Download ACTK:
http://www.microsoft.com/en-us/download/details.aspx?id=7352 Required settings:
Compatibility Mode: - Windows XP Service Pack 3.
Compatibility Fixes
- EmulateHeap
- ForceDirectDrawEmulation
- IgnoreCRTExit
- IgnoreFreeLibrary
- NoShadow
Select all EXE recognition criteria
My Windows 10 is a clean installation. (First upgraded Windows 7 to activate 10, then wiped the entire drive and re-installed from a CD using an ISO.) To make sure I had the latest PS:T version, I downloaded the installer from GOG.com.
- Installed the game.
- Noticed that it used DDRAWFIX, setting "Force DirectDraw Emulation" by default.
- Noticed that it had set "Run as Administrator only" in the compatibility settings of Torment.exe.
Because I wanted to try to run as cleanly as possible, I:
- Removed DDRAWFIX.
- Removed the "Run as Administrator" check.
Torment started flawlessly. It runs the intro video. There are no mouse cursor trails in the menu screen. The game plays as it should, without any problems (as far as I have been able to determine; can't cast any spells yet to test spell effects). It closes down without crashing.
Torment now runs without ANY compatibility settings, and if this game runs well, I'm confident that any IE game will be able to, in some way or another.