Here's a short little write up on getting Age of Mythology (great break down by staff here )running under Virtualbox. I'm running mac OS 10.15.4 but this should work under all platforms using VirtualBox.

Afteri some trial and error, I  found that VirtualBox 6.1 wasn't working with 3D acceleration under XP (apparently it's been removed) so I had to downgrade to 5.2. 

We'll need DirectX support for games anyway, so download that here. You'll know if DirectX isn't working because you'll get a blank black screen with sound, but no controls.

Boot XP in Safe Mode (Hold F8), since the Guest Additions only allows DIrectX support  to be installed under safe mode . 

Once I got Age of Mythology installed, the first error that came up was an unsupported graphics card:
 

This graphics card is not supported by Age of Mythology.
Please check http://microsoft.com/games/ageofmythology for a full list of supported graphics cards.
Age of Mythology will now exit.


Video Card 0: VBoxDisp.dll VirtualBox Graphics Adapter Vendor(0x80EE) Device(0xBEEF)

Makes sense since it's a virtual adapter and the game has no clue what the hell it is. So we have to add the adapter to the available list!

Following this post on Stack Exchange, our vendor is 0x80EE.

So we create a graphics adapter file in 

C:\Program Files\Microsoft Games\Age of Mythology\gfxconfig 

C:\Program Files\Microsoft Games\Age of Mythology\gfxconfig2

We're going to name it 0x80EE_vmware.gfx

[config]
Vendor=VMware
defaultdevice=CyberBladeXP.gfx

[knownGoodDriver]
Month=9
Day=21
Year=2009
Product=0
Version=0
SubVersion=0
Build=0

[device]
0x405=CyberBladeXP,CyberBladeXP.gfx

After that, you'll want to start the game in a safe mode, with low graphics. Create a shortcut to AOM and add these arguments:

"C:\Program Files\Microsoft Games\Age of Mythology\aomx.exe" xres=800 +noIntroCinematics bpp=16 +window +lowend +terrainHalfDensity +lowPoly -waterbump skipMipMapLevels=1 graphicDetail=2

And voila! That's pretty much it. It's very convenient having portable virtual machines as well, especially for old school games. I'm glad there's still people trying to get these older games working, as some of the forum posts are from as new as 2019. The game itself was released in 2003!