On the subject of level transitions, it's worth noting that Flying Battery is the only zone without any kind of intro and Sonic just spawns standing on the ground ala 1/2/CD.
Actually, the fact they drew a map of Angel Island showing various zones implies they cared to some degree about creating a cohesive world. If you look at it, it explains some of the transitions, like the one someone brought up about Sonic going into a tunnel through a mountain in IceCap and emerging in Launch Base. LBZ is located right next to the snow mountains. In fact, they drew maps for the other classic games as well, even before they introduced transitions. We've seen the concept art showing maps of the Sonic 2 world back when it had time travel and took place in South Island. Sonic CD also has a map of Little Planet for each time zone. And Sonic 1 SMS shows the South Island map between levels. There are also Naka's words regarding the levels in Sonic 2: "The feel (in Mystic Cave) is a haunted-house (obakeyashiki), isn't it. But we ended up making a cave stage instead. When making this map, first we had drawn the island, there was a cave, there was a lake, a mountain, a construction site, we were thinking of all these areas. Like Sonic would be here at first, and then he'd go someplace else. That was part of the cave." And if you look at Sonic 1, it's clear that the zones get more industrialized as you go on, with the sole exception of Labyrinth Zone (as it was originally intended to be the second zone). So yeah. I don't think things like level order and transitions were decided as arbitrarily and without thought as you make it sound.
The narrative of the game for sure. Such as level order, themes, a general “arrangement of ideas”. However, the in-game cut scenes themselves were experimented on at the scene and worked out. It was secondary to the levels themselves, but they were great opportunities to make each level stand out with some unique transition.
Just to add to this - as well as the "Zone 8" label in the concept artwork, remember that the prototype contains leftover data from a pre-split version - although Lava Reef Zone seems to be the only one for which full layouts/art exist (and even then only Act 1 for the art), it does include an object layout and a quite different leftover palette for Mushroom Valley Zone, implying it was already implemented in some form pre-split. Interestingly, the object layout doesn't match up well with the level layout in the Sonic 3C 0408 prototype either, so it's pretty indicative that the Zone had a bit of an overhaul layout-wise post-split.
I'm a bit surprised by the debate on the purpose of Robotnik's satellite in Mushroom Hill Zone Act 2. There's an excerpt from the Japanese Sonic 3 manual that makes the purpose of the machine pretty clear, if the in-game season changing wasn't already obvious: This quote would seem to point to the satellite machine in Mushroom Hill Zone, as there's really nothing else in the game that fits that description. As for the original question. I do believe that had the November 3rd, 1993 Sonic 3 prototype been a full 24 Mbit "Sonic 3C" build, we would've had more insight into how a transition into Sandopolis may have played out. Most of Sonic 3's levels have a level layout designed around a planned transition. In the prototype, a lot of the hallways, tunnels, edges, and etc. were already designed despite most transition programming being incomplete. As McAleeCh pointed out above, an early layout was already completed for both acts of Mushroom Valley Zone, so perhaps we could've learned something from how the ending of Act 2 was laid out. A theory that I've thought about before is that the Knuckles "wind trap" cutscene was originally intended for the transition to Sandopolis at the end of Act 2. The reason being is that the Mushroom Valley Act 2 object layout really doesn't seem designed with an intro cutscene in mind. Of course, it's just as well possible the cutscene wasn't planned at all yet, but it's fun to consider what they may have been thinking.
Death Egg doesn't exactly start off with anything special either, I'd say. Sonic just kind of jogs in from off screen at the opening of the level. I suppose one could argue that in itself is an intro, but then it's just so underwhelming compared all the other intros we'd seen thus far.
I'm not saying they didn't think about this stuff, but in the end, gameplay came first, and the small inconsistencies seen in the final product are a result of them prioritizing the actual game over narrative flourishes like this. They had no problem just flat-out swapping levels between the two games after all.
If only Sega hadn't made that deal with McDonalds and had allowed Sonic Team to actually complete and release the game as a single cartridge. It is evident that they did put a lot of thought into the flow of the zones and the transitions between them. I wouldn't say they priortized gameplay over the narrative that they crafted with care. Gameplay was just as important, but this was the swansong of the Genesis series. The shuffling of levels and alteration to the narrative flow was only done out of neccessity, and judging off comments made in interviews regarding zones like Ice Cap and Flying Battery, they weren't pleased with the sacrifices they had to make to meet Sega's deadline. Out of all the transitions, it seems that they were most proud of the two that got cut: Sonic getting launched out of a CNZ cannon to FBZ, and then breaking a door off of FBZ to snowboard on down to Ice Cap. With the care put into those as well as those that made it into the game, I'm certain they had a fun transition planned for MHZ into Sandopolis.
It would be the coolest thing if in Origins they allowed the original intended zone order with the planned transitions. Of course, if CD's Retro Engine port is anything to go by, Sega won't want to include content not in the original.
Do we know the cannon would have been involved? Couldn't Sonic have just grabbed on like he did in Sonic & Knuckles? For whatever it's worth, the end of Zone cannon was absent in the Sonic 3 prototype. But that might not been anything other than the Zone transition not being implemented.
Additionally, it's interesting to me that Knuckles' Marble Garden Zone: Act 2 and Carnival Night Zone: Act 1 transition is also simply running in to and out of levels, that transition stands out me as particularly bare-bones and lacking eventful / substantial connection.
I thought the split was because the cost of a cartridge that could hold the whole thing would have been hideously expensive, or that the Genesis flat-out couldn't handle a cartridge that big. The whole McD's deal thing was just Naka repeating a PR justification because saying "we couldn't fit the games on a single cartridge" would have been too nerdy and technical-sounding for a game meant to be played by 10 year olds. Like I was born in 1995 and as a kid I remember that the technical knowledge of gamers was a lot lower besides specific nerds. You certainly weren't hearing words like "teraflop" being thrown about, nor were you having console manfuacturers boasting about their tech in such plain detail like Microsoft does with the Xbox these days. For Kid Frostav game consoles were magic boxes that made fun happen and I knew absolutely nothing about their inner workings. I can only imagine even earlier it was much the same, especially since gamers who were around back then (like @Josh) talk about stuff like boasting about their favorite console's bits even though they had no clue what the hell "bit" even meant. Or I could have just been an ignorant dumbass kid
The McDonalds promotion was definitely a real thing, I even still have a couple of the toys. Cartridge size was never an issue, as even after recieving the mandate to split the game in order for at least part of the promised Sonic 3 to be on store shelves in time for the promotion, the team was still planning on releasing the full game one cartridge in Japan upon completion of the S&K half. In regards to the Carnival Night to Flying Battery transition, I'm pretty sure it was meant to involve the cannon and not have Sonic simply grab onto the ship. I have yet to track down where I read that though.
We would have that SVP version of Sonic 3 with the polygonal Sonic in the Special Stages if they never did the McDonalds deal.
That's true only to a certain extent. 'Gamers' (for lack of a better word) are probably more aware of hardware now than they were in the past, but tech buzz words were all the rage in Sonic's heydey. The 'bit' wars are a perfect example and were propagated in school playgrounds. Sonic was even a flagship title in this regards because of the malarky around 'blast processing'. It was all poorly understood and had a lot of misinformation but people knew the basic ins and outs. People knew that the SNES was on balance more powerful than the Mega Drive and this continued into the next generations. I didn't know anyone besides myself who had the Xbox but everyone knew it was the most powerful console. Also, the McDonalds promo was genuinely a big deal. I have a hazy memory about it because it happened when I was so young, but even when I was 5 (in 1996) and it was a few years after the deal, I remember kids trading the toys in school. This is how I got Knuckes sitting on a cloud.
