( i noticed a glitch, there is probably loads) Its not like the original that got removed. Instead you click birds at the top of the screen. You click Pairs of 2 to get Health. You have a timer so get as much Health as possible... then you fight. Complete a Level to unlock Dr Pig's Lab Everytime you complete a level you have a chance to spot a Intruder Ship.
This is still a beta so don't expect it to be the best game you have ever played. Thanks to @N1ntendoCoder372 for making this project SO much better. Check him out. He is making his own version of Angry Birds Fight aswell, play his remix's now