Looks great!! On a phone and it looked awesome. My guess is campaign though. I doubt they would put a boss of that size in Invasion. I could be wrong though. My guess is online co-op campaign is its possible, since the other split-screen pics had the split-screens in them.
King of the "Highness"/ Member of the Dangerous 4/ FC/Site in Profile Very Excite for Metroid: Other M and TCon2 (Ninja'd)
That's likely just single player. They did say there were other people already in the area you fight the leviathan. The AI will fight other AI if they aren't on the same side so that would explain why he is firing at the leviathan. My guess is most of the guys shooting at you before start focus more on the leviathan after it starts to attack.
Everything I've learned about life can be summed up into three words: It goes on -Robert Frost