General

I can get it to work in windows 8...sometimes... what seems to have worked for me:
For starters, I have windows 7 and 8 both installed on separate internal drives.

First, I installed MS on windows 7, it works there...

Then I reboot into windows 8 and install MS there (each installation is in its respective C: drive)

Now I can run MS from the previous windows 7 installation, which appears on the E: drive for me (It might be different for you).
Also, I didn't run MS in compatibility mode either. Well, actually, I tried it without compatibility, it didn't work, tried with compatibility, didn't work, then without compatibility again and it worked...

I also tried a similar approach on my laptop that worked. I just had the game installed on an external hard drive, then installed it on my win8 drive and ran the GameLauncher from the external hdd and it worked.

Maybe this can help some people...

It was the same in Windows Vista. Aside from Windows 8's UI changes, much of the OS's structure is nearly identical to Windows 7, but I can't test this because I ran Windows 8 in a VM and I am unwilling to attempt to run MS in a Windows 8 VM.

What I'm wondering is if people are seeing the "This program is incompatible with this version of Windows" popup and figuring "it doesn't work", and just closing it instead of clicking the "don't show me this message again" box and ignoring the message.

That happened on Windows 7 as I recall and while the game did work, you had to figure out that you had to get past that popup first.
Maybe Windows 8 is the same way..?

I have seen some rare Basilers report successfully running Maplestory on Windows 8 r. 8400. No tweaking was seemingly required for those individuals.

I'm right now running MapleStory on Windows 8 Release Preview. Maybe MS is faulty on older versions of Windows 8 but I can play it just fine (It still gives a uncompatible popup message, but worked just fine)

There was one other report of someone who had installed the Windows 8 preview and had trouble with Maple.
The thing is, this isn't a complete release of Windows, just a "preview" of what it's going to be like when it's fully completed and commercially released, to get an idea what it's likely to look like.

It's not fully optimized yet, and commercial products (like Maplestory) most likely haven't yet finished testing for full compatibility with the new Windows, or to make changes to make their products work on the new version.

I don't remember exactly what happened in that other case, but I'm guessing it involved a full reinstall of Windows 7.