After 50 blocks suddenly the tower starts to shake heavily no matter how concrete and balanced. I was at a perfect tower (not even one square sticking out) when on the 50th blocks everything started to swing. 10 blcks later it collapsed without having made a single mistake.... chk the physics there - this isn't even close to natural...
mission 6 - first time i killed the guard before the dude get out of plane then he walked past the guard as nothing was going on - i cant do it again though