Smile every day
This is an epic fail!
It should be easier to play a game with a friend.
I found this ways on Days of wonder forums:
A friend and I were battling this same problem tonight as well. We finally figured out how to get a private game to launch, but I'm pretty unimpressed with the way this is designed, if it is indeed operating as designed:
Player 1 selects the Game Center tab in Online, selects Player 2's name and invites them to a game. On the next screen, Player 1 has to press start before the invite is actually sent. Now here's the key: when Player 2 gets a notification of the game invite popping up briefly at the top of his device, he must tap on that notification before it disappears! If Player 2 does so in time, then a screen pops up that shows the two players and their connection status, until both are listed as connected and the game can start. But if Player 2 doesn't click on the notification bar before it vanishes, there appears to be no place within the game itself to accept a multiplayer invite! Clicking on the notification itself is the ONLY way.
If this is really how it was designed to work, then whoever came up with the design ought to seriously rethink their vocation.
Please Days of wonder, fix this! It's a basic feature!