What are the rules for this game jam?

You have one week to create your game, the Speccy Jam dates will be announced on the front page.

You can use absolutely any tool or game engine to create your game, and it can be developed for any device or platform (Web game, flash game, iOS / Android, PC, Mac… anything you want! It’s entirely up to you) but the finished game must have the feel of a ZX Spectrum game and follow the rules.

The game must have a resolution of 256 x 192 …. but you can upscale this so your game looks much larger and retains the correct resolution (giving it the “pixelated” look).

You must only use the below 15 colours (you don’t have to use them all, but you can not use any other colours)

If you really want kudos for your game, implement the “Attribute blocks” rule .. not essential but this will help bring an authentic look to your Spectrum style game – (more information below).

It is encouraged to make your game sound like a Spectrum game as best as you can. Spectrum’s had very distinctive “Beeper” music and sound effects (Many examples can be found online / youtube). It’s encouraged to create music using a variety of “saw” waves and sweeps, and using only 3 channels. Sound effects on an additional channel. We realise tracking down the authentic chipset sounds and trackers may be difficult, so as long as it sounds retro / 8-bit, it will be acceptable.

There was no game “theme” on the first Speccy Jam, but this year (2nd Speccy Jam) there will be a random theme for each participant. More information to come on how you find out your theme.

To get involved with Speccy Jam, you must register at the Speccy Jam Forum, where you can submit your game project!

Colour Information:
The ZX Spectrum had a very vibrant colour palette of 15 colours.
(8 bright colours, and also the dim version of each, excluding Black which had no brighter / dim version, it was just Black for both.).

Below image taken from http://en.wikipedia.org/wiki/ZX_Spectrum_graphic_modes

ZX Spectrum Colours spacer Hex Codes:

Dim colours Bright colours
 #000000  #000000 black
#0000CD #0000FF blue
#CD0000 #FF0000 red
#CD00CD #FF00FF magenta
#00CD00 #00FF00 green
#00CDCD #00FFFF cyan
#CDCD00 #FFFF00 yellow


Tips to make your speccy jam game look more authentic


Frame Rate

Through consultation I have been advised of the following:
The Spectrum’s display ran at 50fps. That’s the rate at which the ULA fetches the screen from RAM and outputs a video frame. As such, that’s the upper limit. However it would depend on the CPU and the complexities of the game itself and some other stuff – so to make your game look authentic it is advised you go no higher than 25fps. There’s no real lower limit, so to make your game look really degraded you could go as low as you want (but still make it playable of course!).

I have been advised that some typical Spectrum game frame rates were:
25fps, 17fps, 12.5fps, 10fps, and anything below. I recommend you experiment with each to see how they fit the look of your game!



ZX Spectrum games had BIG borders, and could be any of the 8 basic colours (not bright).
To give your game that authentic look, implement the borders like so:



Attribute Blocks

This is a guide for the colour limitations of the Spectrum with regard to “Attribute Blocks”.
I figured to follow this would make the jam very difficult, and only hardcore jammers need to follow it.

Attribute Clash (colour clash)

When a third colour was introduced, this resulted in an effect present on a lot of Speccy games, known as Attribute Clash (where the entire Attribute block would change to the colour of the one that was touched by the third colour)

You can see the sprite in the above image has affected the attribute blocks of the background it is touching, and the colour has changed. Programming could determine whether the sprite attribute would change to red (of the background) or the background attribute would change to white (of the sprite).

(Actually the game above: “Knight tyme”, was one of the few games where players could choose the attribute clash of their choice in the menu before playing! i.e. whether their sprite would be coloured by the background, or the background would be coloured by their sprite)

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