I'm talking about this Microsoft Application Compatibility Toolkit. I downloaded it to see if it could assist me in my epic "Quest Against The Speedy-Gonzalez 3D Graphics Of The Earlier Windows Games" (currently Resident Evil and Nightmare Creatures, more to come for sure...) but I was disappointed.
I mean, the package is meant to solve compatibility issues for stubborn Windos games&applications but I've found nothing to help me in the aforementioned quest. Surely I'm doing fine with Mo'Slo 4Biz, but waiting to buy a new, old Pentium-powered retro system and hoping for the rise of the mighty DOSWINBox (it will happen, eventually....) I would have liked to score some point anyway....
Does anyone use the ACT to make his/her/its preferred game run once again on new (Windows) machines? I'm just curious....

How would you do that?
We use this at work for testing our applications, but I dont see how you could get it to help in games?
Maybe the WinLie would help, if you cant install a game (say it was win 95/98 only) or a patch for a game that has an OS check?

Compatibility Toolkit was THE way to play Dungeon Keeper back on XP. Since then, the display drivers and gfx card's architectures make it impossible to play on modern systems. All hope lies in VM's, when they realize people are willing to get VMs to play older Windows games. Anyhow i've used MACT for a few games back a few years ago, and it helped quite a lot.

The ACT really won't help you that much. If you've seen my compatibility list then you'll know that I've tested a ton of games and less than a dozen require the ACT.
The most common things used which are already part of the compatibility tab in Windows are the 95-98-2000-XP compatibility modes which are the most usefull (IIRC 98,98 actually force affinity to one core).
As for Dungeon Keeper if it's Vista 32bit+ then the last time I test you needed to run it using Vmware Workstation 6.5 with Windows XP 32bit as a guest OS, you'll also need to run it using 95 compatibility mode.
If you don't want to use Vmware then you can try install the XP video card drivers in Windows Vista+ (if your card has XP drivers). Last time I tested the game wasn't compatible with NVIDA/Intel WDDM drivers only XPDM drivers.

I had mouse issues on VMware Player and VirtualBox, apart from that window scaling was screwing with thegame resolution. I've tried it on XP and Win98 machines. There were also screen issues [black screens] which are connected to the VM's display driver and the way it handles dynamic resolutions, also, there were problems with running the game in fullscreen, and not a tiny 640x480 window.
There's still a long way for VMs in the gaming department, DX 6/7 support is still experimental [VBox] for example.
As for the drivers, i'm using a x64 system, and i've tried XP drivers, but it didn't work out well.
As for the MACT, it was required to use on XP for DK to emulate heap, because standard win95/98 emualtion didn't do it afaik.

95-98 compatibility mode do enable the "EmulateHeap" option, only time I remember having to enable that specifically was 2000/XP days it's possibly they updated it in newer OS's or applied an update or something.
I believe DK worked fine for me in Vmware, it's possible the host video driver or screen had a factor as far as scaling to fullscreen. Note again that I was using Vmware workstation 6.5 and XP, not Player so possibly a difference there. I'll check it out again one of these days....currently going through my games and testing them in 7 64bit so it'll be awhile before I get to DK again.
I don't remember any issues with the mouse but alot of times with games in a VM you need to disable or uninstall the mouse additions to get the mouse to work properly.
For those interested here is the list: http://vogons.zetafleet.com/viewtopic.php?t=8784
Soon to be updated next week.

Yep, I know about your list but I still have to find the time to go through the valuable information it contains :-P
I knew my try with the ACT was doomed even before I installed it but I wanted to see it with my bare eyes though....

Yeah usually the issues with these games are video card or speed issues which are really beyond the scope of the ACT and more the realm of driver fixes, wrapper, emulation or if there is source code available fixes to the actually game code. Very rarely will the ACT do much for those games. If you look through the compatibility database with ACT it's mostly superficial fixes applied to the games. (Getting rid of an error during install about too much/little disk space, lying about windows vers, applying compatibility mode, etc).
Basically MS put so many fixes into 95/98 compatibility mode that if a game doesn't work with those then very rarely resorting to the ACT will do anything.
It did help me get MissionForce Cyberstorm working back in the day tho. :)

DK Gold had problems on some machines, for example, on mine, it ran fine, nut on my friends it did not, despite the same OS, then we've learned that people use MACT with that emulateheap, and it worked fine. Perhaps missing a hotfix, or having a 'bad' hotfix was the case that made the difference.:)
No, I've tried it on Workstation too, but trial only, Player is just a free version, fully capable of running games.No difference there. I was pleasantly surprised to see so many of my games working on Win7x64, System Shock 2 with Kolya mod is one. Age Of Empires had some funny errors though, AoE3 claimed it has compatibility issues [an M$ game on a M$ OS, huh;P] and AoE2 required my friend to shut down explorer.exe before playing. ;>
Without the addition the mouse was sluggish and skippy, with the additions it had a nasty habit of jumping to screen edge/corner.;]

I forgot I setup a Windows 2000 VM in Vmware 7.0.1 on my test laptop with host 764bit so I did some testing.....
Dungeon Keeper Gold
Tested 3/5/2010
Installer is 16bit. Install game on another computer and copy the files over. Modify "keeper.cfg" if CD drive location changed.
For both instructions below you will need to end the explorer.exe process before starting the game otherwise the palette will be corrupted.
TO RUN GAME IN DIRECTDRAW
Just execute the game.
TO RUN GAME IN DIRECT3D
Run game in Windows 95 compatibility mode.
Also install the Windows XP video card drivers for your video card.
Tested on Dell XPS M1330 with Intel 4 series chipset
VMWARE v7.0.1
Game didn't seem to work using Windows 2000 as a guest OS.
OLD
Tested 10-16-2008
Tested using Vmware Workstation 6.5 with Windows XP as the guest OS.
Run the game in Windows 95 compatibility mode.