I am a huge fan of the chaotic nature of the battles and architecture of the first part of the game. It seems unscripted, and I like the cramped style of combat. It prevents the ridiculous "Run in circles around the enemies and let them kill each other" technique, which is common in large battles.

I ended up taking the timeline where you get infected, and I was having a good time with those levels, though they are somewhat less fun than the ones where you cooperate with humans. I got stuck on the lava level Jjaro Jjaro Revolution. I ran through it about 30 times, getting farther each time, but I lost hope after a while. It's just way to hard, and minutes of focused killing can be obliterated because you just got knocked off into the lava. I'm okay with long stretches without a save terminal, but that was too long.

So to summarize, the first few levels were amazingly refreshing, and reminded me how I used to feel playing the original games oh so many years ago. It loses that charm towards the middle of the game, though continues to be very good.