Just beat Act 2.
I think Act 2 is the hardest in a sense since there are large areas and when you get spotted, you have to start from the beginning. It’s like a puzzle of what to do to get to the exit without getting spotted, with many attempts.
Metal Gear Mk II is pretty useful since you can apply stealth camouflage on it (without penalty) and remote-control it to stun enemies within reasonable distance.
It’s pretty strange, but in case you don’t know, one of MG4’s marketing points is ‘sneaking on a battlefield’. This element turns out to apply to the first 2 Acts only (and even then it’s not as grand as it’s made out to be, a lot of orchestrated stuffs). Moving forward it’s mostly boss battles, more conventional sneaking and some on-rail shooting.
My playtime is now 1hr 40min. Seems pretty okay so far.
Tomorrow is the release of Metal Gear Solid V Ground Zeroes huh. Probably a few more days before I can get my copy ^^;