I got to thinking about the levels in Sonic 3 last night. I ended up wondering which act is objectively the hardest of them all. I concluded it must be 9-2, aka Sandopolis Zone, Act 2, for several reasons. 1. Lack of shields. Now I'm not an expert on everything in this level and it wouldn't surprise me if there's more shields here than I'm aware of, but it does definitely seem like there's a lot fewer shields than in most acts. To be honest I only know of one, shown in the pic, near the starting point. 2. Endless loop maze (I guess there's probably a better term for this type of thing but I'm not sure). It's confusing at first until you learn the correct path. It winds down the clock, which I've often heard players talk about how this act is unusually time consuming. And in fact it is a relatively long act even if you don't get lost, several of the other zones can be completed in their entirety in the time it takes to finish the content of this one act. 3. Timed doorway switches. Again, maybe there's a better term for these than "switches", but whatever. It's a gimmick that appears frequently throughout the act. It's not much fun to interact with, and the ticking sound it makes during the countdown is loud and obnoxious, making it pretty tedious at times to have to deal with. The fact that they're timed makes it a lot tougher too, the designers did a fairly good job ensuring that some switches really challenge players to get through the doors before they close in the time allotted. 4. Scorpions (Yet again, I apologize for not knowing the proper name). I have to say, this enemy must certainly rank in the top-tier for all enemies in the game. I can't think of any other enemy offhand that is as consistently dangerous, aggressive, and formidable as these things. They're pretty cool, IMO, and I think you can tell a lot more thought went into these things than such enemies as Rhinobot, for one. Killing one involves knowing how to manipulate it's behavior in such a way as to create a safe opening to attack it from. That or having a certain... swagger about you, that you're able to react to its movements quickly enough, and correctly, to execute a counter- or preemptive-attack. 5. Auto-scrolling. If you don't go clear the obstacles fast enough, you'll be crushed, no different from the auto-scrolling segments at beginning of HCZ2 and towards the end of MGZ2. The nature of autoscrolling is that it's more punishing and less forgiving of errors compared to other gimmicks and non-autoscrolling areas, which helps to foster a feeling of being pressured or even panic if things get ugly, for the player. It's something that's only used in a few different levels and even then only in short bursts, so in my mind the mere presence of auto-scrolling in 9-2, in addition to everything else this Act throws at you, scores extra difficulty points. 6. Lights. In a way, this is like a second timed switch gimmick to be kept track of. You need to always keep in mind the current lighting inside the pyramid, while also keeping an eye open for the switches that relight the candles. This requires you to multitask and serves as a distraction from the main action that's going on. Just in case anyone's wondering, I separated the lights from the ghosts because until the lights actually go out, the ghosts are little more than additional indicators as to the time remaining on the most recently activated light switch. The two are so closely related to one another, though, that I could see consolidating these last 2 points into 1. 7. Ghosts. I'm not sure whether to classify them as a gimmick or an enemy, but whatever they are, they're iconic and memorable. No other level has anything like them. What they bring to the Act in terms of difficulty is basically a more frantic and intense multitasking game than in 6. If you're busy managing the ghosts, that affects your decision making, making it easy to overlook minor details. If you miscalculate a jump and land a little bit off from where you intended, there's a good chance you won't be able to react in time to avoid getting hit (either by the ghosts or something else) because you weren't predicting that you would've needed to. In other words, the real threat of the collective ghosts isn't that they will attack you, it's that they will distract you. So yeah. Lack of shields, a looping maze, situational timed switches, advanced enemies, auto-scrolling, ongoing timed switches, and to top it all off, Ghosts. I don't know of any other level that contains such an amount and variety of content, mixed together in such a challenging combination.