I just got my email accepting me into the Alpha. I encountered an issue that prevents me from joining any online game. This is the sequence of events:
1. Installed game on iPhone 5 (iOS 9)
2. Trusted 2D Boy LLC
3. Ran Subterfuge
4. Played through puzzle missions until security level 1
5. Created new account
6. Verified account by email
7. Returned to subterfuge
8. Got error saying "Login Failed. Please login again"
9. Typed screen name and password
10. Spinner spins for a looooong time. Never logs in.
11. Installed game on my iPad Mini 3.
12. Trusted 2D boy
13. Ran game.
14. Tapped online game. Turned on notifications when prompted.
15. Prompted for login.
16. Login succeeded. Able to see games.
17. Noticed banner at top of screen saying notifications not enabled.
18. Switched to notification settings noticed that all notifications were enabled for subterfuge.
19. Switched back to subterfuge. Still had red banner.
20. Closed subterfuge by swiping upward in running programs view
21. Ran subterfuge
22. Got "Login failed. Please login again"
23. Attempted to login again
24. Got endless spinner like I did with my iPhone.

Now neither of my devices can log in.

Note: I uninstalled and reinstalled on my iPhone and could then log in and join a game. But then while doing one of the intermediate puzzles the game crashed and then I went back to the indefinite spinner when logging in.

are you on a wifi network on cellular?

Wifi. And the connection is fine. I've since uninstalled and reinstalled 4 or 5 times. First login always works fine. 2nd goes into infinite spinner.

All right, I believe this is fixed in the last build.

Give it a try. It should just start and ask you to log in again.

Confirmed, it works now. It'd be nice if it actually remembered my login credentials though, but at least I don't have to uninstall and reinstall to login again now. Kudos!