Why wasn't Sonic CD featured in Sonic Mega Collection Plus?

At the time I thought it was Naka-san being childish and not allowing one of the best Sonic games ever made in the collection, because he didn't work on it.
But then I read somewhere years, back that it was down to sound issues.

 

What I want to know is why they even tried to emulate the Mega CD when a C port of the only game that was going to use the emulator already existed.

 

It's still software that was designed only to run on a Windows 95 pentium PC that needs to be ported over to a completely different architecture, that's still a big project that needs resources. From the snippits of interviews above, it sounds like they started with the emulator then decided to use it to do a Sonic compilation. Using the PC port probably wasn't even on the radar at that point.

 

Speaking of which. Was the MCD so hard to emulate that they opted to instead port the Windows version of SCD? They already had a working MD emulator, wouldn't expanding it to support the MCD processor and features have been faster and easier than porting the game from scratch?

And how come the water in Tidal Tempest was invisible? Even if contemporary systems didn't support palettes, I imagine it would have been rather simple to put a transparent rectangular mesh as an overlay in front of the camera to give the water color? Granted, it wouldn't have looked identical to the original game, but it would have been better than nothing.

 

Another possibility is that they were struggling to get good performance out of an emulator on that hardware? Genesis Plus GX for example doesn't quite run at full speed on GameCube (it's amazing on the Wii of course), although it's trying to run all software so can't just focus on doing Sonic CD well like a commercial emulator could.

The water sounds like an effect done in a very 'Windows PC in 256 colour mode' specific way with no obvious equivalent on those consoles. Although leaving it completely clear seems like a horrible 'alternative' if you can call it that.

 

If I had to take a guess the issue would have to stem from actually emulating the CD drive itself and reading data off a ROM, rather than the software part of that. But keep in mind my sig

 

Having recently extended my Mega Drive emulator to a Mega Drive+Mega CD emulator, I think I can safely say that emulating the Mega CD is a massive pain in the ass. Not only do you need to emulate a second Motorola 68000 CPU (which is a huge problem if the 68000 emulator that you are using has global state and therefore can only emulate one CPU), but an additional sound chip, and a CD drive controller chip (which the developers may not have had any documentation for, and which carries with it all the baggage of reading data from a 700MiB CD image that you cannot possibly fit in the GameCube's 24MiB RAM).

Also, the Mega CD operates on its own master clock (50MHz), which differs from the Mega Drive's (52MHz), which makes synchronising the CPUs/audio chips far more complicated, as you can no longer just assume that the smallest measurement of time is 1/52000000 seconds and time everything based on that. If you instead force the Mega CD components to be emulated with the Mega Drive's master clock, then the audio will play at the wrong speed.

Not only is implementing all of this a ton of busywork, but it also greatly increases the emulator's system requirements: emulating the Mega Drive's 68000 and Z80 CPUs is already enough of a workload, but emulating a third CPU which is clocked higher than both of them combined is going to push the GameCube much harder.

So why do all of this when you can just port a PC game that is already designed very similarly to a GameCube game? It is written in C (as opposed to a GameCube-incompatible flavour of assembly), targets a then-recent 3D rendering API (instead of the Mega Drive's wacky 2D 8x8 tile system from the 80s), and stores its code and data in a modern filesystem (instead of a giant 100MiB ISO that only the game itself can parse). It sounds like way less effort to me.

Years ago, I ported the original freeware version of Cave Story to the Wii U and 3DS; that game used a similarly-ancient version of DirectX, and yet porting it to newer platforms was really not all that hard. Making my Mega CD emulator was by far the more difficult task, so I do think that it came down to porting the PC version of Sonic CD being easier than making a Mega CD emulator.

 

I mean, I think the very recent MD Mini 2 by M2 was the first instance of SEGA officially emulating Sonic CD. They are FAR behind fans in terms of this stuff.

I feel like they made some attempt with Mega Collection, realised it was FAR beyond what they could do at that point, and opted out, with them deciding to add it via a port when another collection was approved. I think the fact they decided to go all the way porting it over retry emulation shown how limited they were with emulation back then. Likely also why we didn't get Chaotix in any of these collections.

Really of all the games they don't rerelease, I think Eraser is the only clear 'could but won't' choice (it was even programmed into Gems' menu), though that might also have some copyright complications due to the whole modem deal. I'm sure they'd gladly have distributed CD, Chaotix and SEGASonic as much as they do 3D Blast, Spinball and the 8 bit titles if emulating them was as easy a task, but them being on separate harder to replicate consoles I think makes them more work than SEGA are willing to put in, especially with few other titles on those consoles to make it a sizable investment.

 

The Image crossover blanked out the faces of Image characters. There might be more stuff.

That depends if it was actually cancelled in the first place. There is such a thing as simply not bringing something over (Like a lot of games that have Xbox versions in the West but not Xbox version in Japan).