So the new aliens have red mojo unlike the old ones, the question is why i wonder if it will be explained. What happened with the old ones, and the flying octopus, which i thought was awesome. Is that like alien upgrade from blue to red?

True that I was wondering? I think it's because we found an ancient civilization at the Island. So they are the old warrior aliens, whilst the ones in NYC are new ones coming from their home planet

If you ask me, they changed it probably because they wanted to head into a new direction. The aliens were pretty cool in Crysis 1, but with Crysis 2, I bet they wanted to do something new.

Besides, I think the new aliens look great! In most cases, the structure of the aliens look exactly like the original naked aliens from Crysis, only that they're wearing armour.

lmao at the flying octopus and the alien upgrade.

Seriously, I think they don't want a too big difference in AI and gameplay comparing to humans. In Crysis 1, most tactics that worked well against the Koreans, had no use once the aliens showed up.