@oteckre
No split-screen multi-player, which is unfortunate for those who only have one pc.
@boldee
There are a lot of possible reasons for this.
I haven't attempted to set up a multi-player game with a real person yet, but from what I saw here's how I think it should work:
1) From the main menu, the host chooses 'Multiplayer' enters their name and clicks 'Ok' then selects 'Create Game.'
2) The host will then need to provide his IP address to the client who will be joining.
2a) The IP address is shown in-game at the bottom, but if this IP doesn't work you may need to try your other one.
This one can be found by entering the Command Prompt from Start > All Programs > Accessories > Command Prompt
Here enter the words ipconfig -- this will display your primary IP address under 'IPv4 Address
and your Local IP Address under Default Gateway.
(All this *might* vary based on your OS.)
3) The client can then enter the Multiplayer menu, enter their name, and click Join Game.
3a) The client then should enter your IP address.
The primary IPv4 should be the one that works, but if you're more local to each other, you might need to use your local address (Default Gateway)
Your primary and local IP Addresses should look nearly identical, perhaps with only the last 3 digits differing.
I also noticed when entering Multiplayer, Windows asked if I'd like to allow the game through my Firewall.
If the game can't get through, this might be another reason for the issue you're having.
Another possible solution related to that, is to run your game as an Administrator.
(Right-click the desktop shortcut, click 'properties,' go under the 'compatibility' tab,
tick 'Run this program as an administrator,' click Apply and Ok.)
Running the game as an administrator might help with Firewall issues.
Alt-Tabbing while setting up the game as a host, might reveal a pop-up to allow the game through the Firewall,
if it hasn't already been Allowed.
I'm not sure if that will help you or not, if it doesn't, I might be able to come up with more ideas,
but hooking up multiplayer games over the internet isn't one of my strong-suites.
Vince