Well, beginning from mission 5 game is too hard. Too much need to do, too much places need to visit. Too low time to do this after alarm.
I feel what only one solutions - cleaning level by stealth with silencer handgun, like i did in mission 4.
Maybe needs to do different reinforcement period for all missions.
Now i cannot complete missions 5, 6, 7.
But i completed mission 8 and boss.