I've been beta testing this as well for the past months and I can highly recommend it. The lack of a singleplayer/skirmish/AI is not only by design, but also out of necessity as a usable and challenging AI for such a game is quite a pain to code. I covered this in more detail in this thread over on the official OML Community Forums. To be honest, because the league-system tries to match you based on your skill, you really don't miss a singleplayer - as long as you have a constant internet connection. Pass'n'Play games do work completely offline, but they require your opponent(s) and allies to be physically close to you to pass your device around. There is also a thread with collected tips for new players from a few beta testers over on the OML forums. Have fun!