Announcing Sonic GX - a new episode of Sonic the Hedgehog for Amstrad GX-4000

[Maniac]

I can't add much to what everyone else has said! Simply stunning! 

[OneVision]

This is simply awesome and breathtaking. If only this kind of game had been released back in the days, on many points it seems... no it IS superior to the SMS version.
Kudos to the whole team and that surely leads the way for other productions ...

[scorp6128+]

Unbelievable
Absolutely fantastic work.
Such a great project.

This will be setting new standards for the GX4000 and Plus range.

[Anthony Flack]

It's beautiful. Always great to see an update on this great project, or indeed any GX project. But this one I am especially looking forward to. 

[norecess464]

Thanks all for your positive feedback! After so many hours invested into this project, you have no idea what it means to me.

As a reminder, this is a collaborative effort:
- CeD for the graphics. It's not a simple "copy-paste" of bitmaps into the project, CeD provides his best work to enhance those assets to the GX-4000 constraints
- Targhan for the audio part. If the game feels and plays like Sonic, it's mostly because the audio plays a big part in this!
- TotO for the overall design of the game. He is the "guard", telling me what is good and what is not. For example, it's him that insisted to "do something with the horrible scoring screen" (the previous version was a separate screen), or "the clouds in the Bonus Stage are not the ones from Sonic game!" (it took me time to realize that the reworked clouds of Shadow Of The Beast game weren't appropriate).
- and me for the programming part

Once again, thanks all!

[Maniac]

After watching the video numerous times a question has sprung to mind. In no way is it a criticism @norecess464.

It was interesting to see that you have now added extra bits to Robotniks end of level boss graphics. Such as the swing balls etc. In the Sega games the swinging platforms over gaps also have rings swinging with the platform. Am I right to assume you just don't have enough machine resource available to do this when the environment is scrolling and doing so much other stuff?

[norecess464]

After watching the video numerous times a question has sprung to mind. In no way is it a criticism @norecess464.

It was interesting to see that you have now added extra bits to Robotniks end of level boss graphics. Such as the swing balls etc. In the Sega games the swinging platforms over gaps also have rings swinging with the platform. Am I right to assume you just don't have enough machine resource available to do this when the environment is scrolling and doing so much other stuff?

>  After watching the video numerous times
Ah! So it was you that bumped the number of views in the Youtube video! 

More seriously, the 2d engine I wrote for the GX-4000 can refresh 1 hardware sprite per frame, so refreshing multiple sprites for anything is totally doable (it will take several frames to update a set of sprites, but that's fine while scrolling etc., because they are still hidden and about to be displayed into the game viewport).

No, the real limitation is the number of sprites of the console itself. 16 sprites are a lot, but if you take in account that 4 sprites are used for the hud (ring/live count) + 2 sprites for Sonic + 6 sprites for the rotating rings, we are already using 12 sprites (out of 16). The 4 other sprites are dynamically refreshed while playing and used for enemies, moving platforms, etc.

So you get your answer: not enough sprites to manage the swinging rings for the platforms.

For comparison purposes: the Sega MasterSystem features 64 sprites 8x8 pixels (which is equivalent to the 16 sprites 16x16 pixels of the GX-4000). The Sega Mega Drive/Genesis can display up to 80 sprites (I don't know the limitations). The SMS does not display swinging rings for platforms.

If other people have questions (technical or not!) feel free to ask!

[VincentGR]

I've asked this in a previous post.

Is that road mode 1? Looks better than 160x200.
And also the camera movement. Will it stay lock on sonic, or it will have more freedom like the GG version. It is a bit weird being like this cause it moves very fast when you move sonic.

The game is perfect as is, just asking 

[norecess464]

I've asked this in a previous post.

Is that road mode 1? Looks better than 160x200.
And also the camera movement. Will it stay lock on sonic, or it will have more freedom like the GG version. It is a bit weird being like this cause it moves very fast when you move sonic.

Ah yes, the intent was not to skip you, sorry.

> Is that road mode 1? Looks better than 160x200.
Yes it's MODE 1. My early prototypes used MODE 0 but really, the pixels were too big, and it wasn't nice. The MODE 1 was more complex to manage because with fewer inks I could not get 1 tile->1 ink, but in the end with some clever programming (involving switching to another set of internal chessboard in VRAM for holes) the MODE 1 was a much better approach.

> And also the camera movement. Will it stay lock on sonic, or it will have more freedom like the GG version. It is a bit weird being like this cause it moves very fast when you move sonic.
Yes I see what you mean.
As for now, it's subtle but it's not really "locked" to Sonic. There is a small "cage" around Sonic, cf. when Sonic looks to the right, he is positioned a little bit at the left (of the center of the screen). When Sonic moves quickly from right to left, the camera is slowly moving to right position, and Sonic gets positioned at right (from the center).
Same behavior when jumping, btw.
All of that is about tweaking. Right now, the Sonic management can be tweaked again a little bit, but it feels much better than in the previous internal versions and TBH, I'm satisfied with what is implemented right now in the game.

Those days when I need a comparison, I put my eyes first on the Mega Drive version of the game (especially for game design ideas like the boss fights etc.) and sometimes I look at the Master System (for its tileset usage and enemy interactions, mostly). I admit I have not watched the GameGear version for a very long time.

[dthrone]

After watching the video numerous times a question has sprung to mind. In no way is it a criticism @norecess464.

It was interesting to see that you have now added extra bits to Robotniks end of level boss graphics. Such as the swing balls etc. In the Sega games the swinging platforms over gaps also have rings swinging with the platform. Am I right to assume you just don't have enough machine resource available to do this when the environment is scrolling and doing so much other stuff?

If other people have questions (technical or not!) feel free to ask!

Technical questions here please

Is the aim to fit the final product in 512kb or an expanded cartridge like Bubble Quest?

Are there any interesting new GX4000 emulator / hardware discrepancies you've come across?

[norecess464]

Is the aim to fit the final product in 512kb or an expanded cartridge like Bubble Quest?

Are there any interesting new GX4000 emulator / hardware discrepancies you've come across?

> Is the aim to fit the final product in 512kb or an expanded cartridge like Bubble Quest?
Sonic GX requires a 512KB cartridge and 64KB of RAM. I use the C4CPC from @gerald to test on the real hardware. Those specs won't change for the release date.

> Are there any interesting new GX4000 emulator / hardware discrepancies you've come across?
I use my own fork of CPCEC from @cngsoft to develop Sonic GX. With this emulator, I noticed few technical issues (mostly interrupts vs. ASIC) but I was able to make work-arounds, cf. make it work as I wished on both real hardware and CPCEC.
I did personal tests with RetroVirtualMachine, ACE and WinAPE and they all run Sonic GX very well (to be noted: I'm puzzled by WinAPE that implemented the ASIC emulation at a time where only few homebrews existed!).

[andycadley]

(to be noted: I'm puzzled by WinAPE that implemented the ASIC emulation at a time where only few homebrews existed!).

It was very much a "build it and they will come" situation. I had to twist Paul Hodgsons arm to get him to include Plus emulation in his MultiMachine emulator (which IIRC was first), including writing my own JSW+ that mostly existed to encourage Plus emulation development. That got some interest in imaging real cartridges, so then CaPriCe picked up some Plus features. Then WinAPE came along as the first emulator really focused on just Plus emulation. The rest is history, as they say.

There are a few known issues with WinAPE's emulation as a result of it being so early. Hopefully one day we'll see ASIC details make it into something as comprehensive as the CRTC Compendium and Plus emulation can get even closer to perfect. I'm sure things like Sonic GX will raise the interest level once more.

[Golem13]

(to be noted: I'm puzzled by WinAPE that implemented the ASIC emulation at a time where only few homebrews existed!).

Richard Wilson's work is truly remarkable, and I applaud the existence of his emulator every day.

[jockavelli]

It looks & sounds fantastic, you've all done an amazing job with it.

Can't wait to sit back relax and run through it.

[simulant]

Amazing work, absolutely stunning

[GUNHED]

Probably the best game in Z80 world and beyond! 

[kawickboy]

Fluff in 1994 was supposed to be a CPC+ answer to Sonic, providing a game especially made for the system, but with Sonic GX the gap is unbelievable. Such games like Zool 1/2, Superfrog or Kid Chaos were possible on the system in fact.

I'm agree with you. Now eveyone saw what the game is. Now don't spoil anymore until final release.

[Cwiiis]

Absolutely amazing, glad to see the continued progress and really looking forward to playing it

If I can make one suggestion, just in case it isn't already planned (I expect it is, but still), I think it'd be worth spending some time polishing the physics. By the looks of it, holding a direction instantly gives Sonic an amount of horizontal velocity, but the acceleration is much slower in original Sonic (on both mega-drive and master system) and the amount of acceleration in the air is much, much slower still. Sonic's velocity shouldn't instantly stop when letting go of a direction either, which seems to happen multiple times in this demo - I notice it especially with Sonic's air control, which looks very different to conventional Sonic. I think having velocity and acceleration tracked consistently would make it feel much more polished and more like a Sonic game. But like I said, you're probably already aware too I'm just putting it out there as no one seems to have mentioned it and in case it had slipped, it'd be a shame in what is otherwise such an amazing presentation.

Another physics difference, Sonic clips through Robotnik during the boss stages here, which is inconsistent with Sonic's physical interactions with other enemies and with Sonic on other systems - but I expect this is just another work-in-progress thing.

[norecess464]

Yes @Cwiiis those details will be tackled next year!