Originally posted by me here:
http://www.drmgamecast.com/2015/04/stealth-inc-2-game-of-clo...Here's 6 videos of me attaining S ranks in all 60 levels in the game. If you follow the same path with a bit of practice you should be able to get S ranks too! The videos are split into the 6 areas of the game.
While I do it in the videos it is not needed to complete all 3 requirements in 1 run. You could do 3 separate runs and still have the game credit you with an S rank.
I will note that the times in the first area are really strict and don't leave much room for error, the other 5 are much more lenient. Also 3-Y is really tough for the spots limit as you are in constant combat with your drone.
Area 1Area 2Area 3Area 4Area 5Area 6