Haven't tried it yet, but have read good things about the ambitious UserPatch, which both fixes bugs and improves the game in general. Age of Empires III: Definitive Edition is now officially supported by Parallels Desktop to play on Mac Learn more about this, including the minimum requirements, on in the Parallels blog: Run the new Age of Empires III DE on a Mac with Parallels Desktop. We were of course making sure we ran the same version/patch of the game on both machines. If all has gone well, the game created on the Windows machine should show up in the list of LAN games on the Mac.
Then click Advanced, Tools, Winetricks, find DirectPlay in the list(s) and hit "run". First install the latest release of wine for your OS, guides can be found here. This is preferably done through the Wineskin wrapper's advanced options, reachable by holding ⌘ Cmd when starting the wrapper. Install DirectPlay through WineTricks.Get Wineskin, create a new Wineskin wrapper application, and install AoE 2.Steps on the Mac (game participant) machine For example, I have Age of Empires in my Steam library which is not available on Linux.
Start the game and create a multiplayer LAN game. Game distribution platform Steam has implemented a fork of WINE."Allowing the application" in Windows Firewall should be enough (assuming there no other firewalls have been installed).
In our case, the PC was the game host, and the Mac joined.
Have successfully done this today, playing a two-player game on the same (W)LAN. Playing Age of Empires 2 cross-platform between a PC (Windows 7) and a Mac (OS X 10.10 Yosemite) works - at least if you also play the PC version through Wine on the Mac.