So installer for AI War is not necessary? Just copied files will work if all prerequisites are in place?
Yes. However, the automatic updates will not work if the installer was not used, so that's the most compelling reason to use the installer.
Can you specify why? Registry entry or what?
I'm not sure exactly what it does, it's all internal to Windows and its MSI system. Essentially, the installer is MSI-based (it is wrapped in an exe only so that it can do prerequisites checks). MSI is mostly just an xml script that gets executed by the Windows Installer service. The patches, as you may note, are MSP files which are the MSI-system form of patches. Basically it looks at an existing program that was installed via MSI, and then patches it up to an even newer version.
It's a bit brittle in some ways and I'm not entirely thrilled with it. If anyone knows of some better programs for distributing files in a fairly automated way, then that would be cool. I could probably program something like that myself (I have before), but the main issue is different OS permissions and such -- this other tool has to exist outside the AI War application (since it has to replace that application), and it has to know how to intelligently handle the varying permissions (especially in Program Files) on the various MS operating systems.
With a system like that in place, people could use the MSI installer if they want, or just use a zip file download, and then the patches would work either way. Otherwise, until that point the MSI has to be installed or people have to use the zip file patches instead of the MSP ones.