So how does this game work. Besides the standard KoF fighting, is the only other system the critical counter system?
You can parry now, too. Back and both hard attacks does it. They also made it so that a lot of special attacks will cancel each other out (in other words, not just fireballs stopping each other, but a flying kick special will now also stop a fireball), and even a well-timed normal hard attack will as well.
The CD attack from before has also changed and can be charged up; it now acts more like focus attacks do in SF4.
I get that it activates with a heavy attack that counter-hits when the meter is full, but what are you supposed to do after it starts. Just mass buttons or can you do actual combos? Also is there anyway for the opponent to interrupt/cancel it once you've started your custom combo?
It activates with back and hard punch (hard kick for a few characters). Once you hit a critical counter, combo, combo, COMBO! Button-mashing isn't going to do much in the way of damage. When you're in CC mode, you can do combos and combo in specials that you are normally unable to do. A well-placed CC can do a shitload of damage. I thought CCs would fuck up the game, but they don't...it's harder to land one (once you are used to the game and playing against good players) than you might think.
They do a lot of damage and it seems like you'd just wait and turtle and counter when the opponent got down to 25% HP.
It's typical fighting game fake-out stuff. Bait them into trying to hit the CC (you can see it coming, with the glowing fist and all) and punish them for it, or throw them out of it. It's KOF; you've got different levels of jumps/hops, dashes, rolls, and other stuff at your disposal.
Even though Kyo and Iori are clearly the best characters in the game, it's pretty damn balanced, all things considered. It's a real shame that they fucked up on so much else, but the fighting mechanics are really good.