Steam tells me I’ve clocked 297 hours into StS. I’ve only barely reached I think A17 or 18 with Silent, ~A15 with Defect, and only 1-2 for the other two. Still got a ways to go!

If you really like StS, I can recommend Downfall, a fan expansion for the game. It is not as polished, and the mechanics aren’t quite as tightly wound, but it offers a whole lot of very novel new mechanics and characters as well as an entire new mode where you play as a Boss working your way downward instead of the reverse.