Sinclair ZX80 / ZX81 / Z88 Forums

Hi all,

I'm pleased to announce that I will soon be releasing a ZX81 port of my Spectrum game, "Cosmic Payback", a 3D platform-puzzle game involving a bouncing ball in space.

I had originally intended to release this today, the 5th of March, in honour of the ZX81's 44th anniversary. However, there are still a couple of parts left to implement - and very little memory left for them. That being said, I didn't want the day to pass entirely unmarked, so I've decided to release a small three-level demo of the game to let you have a go at it prior to the full release.

The full version will be released on the 30th of March. That should give me enough time to get all of the loose ends tied up so that I can present the game how I would like to.

In the meantime, I hope you have fun with the demo here! The keys are as follows:

Q - up / A - down / O - left / P - right

EDIT: New version of the demo uploaded - patched to fix issue with star graphics when loaded with ZXpand.

Woaw, this amazing ! I found it to be a little difficult, maybe I'm just too bad.
This seems like a masterpiece !

Just when you think nothing else was possible with the Zeddy!

I shall try this on real kit tonight.

The game looks great, has really nice animation, and plays very well. At first glance, it is easy to miss that it is pseudo hi-res! An excellent job! Looking forward to the full release.

Yep works on real zeddy and ZXpand, what I imagine are the stars in the background turn into lines as it runs so not sure if that is normal or not, otherwise yes great stuff.

Moggy wrote: ↑Thu Mar 06, 2025 6:54 pm Yep works on real zeddy and ZXpand, what I imagine are the stars in the background turn into lines as it runs so not sure if that is normal or not, otherwise yes great stuff.

Yes, my apologies for that. The trouble seems to be caused by the ZXpand overlay ROM - I've now patched the game to disable the overlay (new version in 1st post), and that seems to fix it under emulation.

EDIT: Over on the Spectrum Computing forums, flange has been helping me with testing, and it seems that the issue persists on his setup, even with the patch. I'm going to have to investigate this further...

PROSM wrote: ↑Thu Mar 06, 2025 10:03 pm

Moggy wrote: ↑Thu Mar 06, 2025 6:54 pm Yep works on real zeddy and ZXpand, what I imagine are the stars in the background turn into lines as it runs so not sure if that is normal or not, otherwise yes great stuff.

Yes, my apologies for that. The trouble seems to be caused by the ZXpand overlay ROM - I've now patched the game to disable the overlay (new version in 1st post), and that seems to fix it under emulation.

EDIT: Over on the Spectrum Computing forums, flange has been helping me with testing, and it seems that the issue persists on his setup, even with the patch. I'm going to have to investigate this further...

Flange/Moggy one and the same sir!

The relevant topic on Spectrum Computing forum is this one.

Mark

Moggy wrote: ↑Fri Mar 07, 2025 1:14 am Flange/Moggy one and the same sir!

Funny that - I noticed your signature both here and on SC, but never made the connection!

the zx81 can't do 3D but i'm impressed. Will you be doing ports to other systems like the Jupiter Ace or Sinclair QL?