JetPac for the ZX81

[Bukster]

Here's my first new game post on this forum, a ZX81 version of the Spectrum game Jetpac I finished earlier this year. It has four types of alien and two ships to assemble. This version features re-definable keys and variable difficulty levels which the original game didn't have, so the ZX81 is ahead of the spectrum on those counts.

I had to take some liberties with the game play and alien design to make it playable. The spectrum version had a laser that zipped across the screen. That would have made the game too easy, so this uses minus signs like bullets. The difficultly levels adjust the number of aliens and bullets from four aliens/eight bullets to eight aliens/two bullets. Extra life at 2000 points. The bottom line of the screen tells you what your current task is such as assemble of fuel your ship etc.

Give it a go and see what you think.

JetPac.p

(11.4 KiB) Downloaded 378 times

[zxooner]

@Bukster,

This looks awesome! Can't wait to try it out when the ZXPand+ arrives!

Thank you for sharing it

[McKlaud]

Nice

[Bukster]

I almost forgot, I have also produced an mp3 so you can play this on a real ZX81. I have loaded this and it does work. I always like my game to play on the original hardware. Here's a link to my webpage where you can get the mp3. I don't seem to be able to upload the mp3 to this forum, but you can get it from here.

http://bukstergames.bizhat.com/

There is a certain irony in using a 4.7Mb file to load 16k into a machine. Imagine if modern computers used every last drop of memory and processing power as efficiently as the early computers.

My site contains a few other minor ZX81 programs that I haven't posted here, at least not yet.

[Fruitcake]

Jetpac looks great! Nice work.

Have you considered including Chroma colour support in the game?

If you have a Window PC then you can use winTZX to create audio files from .p files as and when needed. The utility was improved last year to produce more accurate audio waveforms and also to include support for ZX80 files, and I've found it works remarkable well.

[Bukster]

I've exchanged emails with Paul, the person behind the chroma interface. He was very helpful with technical details and my next game, a Berzerk clone will have chroma support. I'l consider revisiting Jetpac and adding colour if I can find the time.

[Shaun_B]

Got it running on my ZXMore - the speed increase / decrease helps for the 'turbo' mode @ 6.5Mhz.

This game is excellent. Thanks for your hard work. It's a shame I'm no longer a writer as this is definitely review-worthy.

Regards,

Shaun.

[JohnsBargs]

Wee bug report, btw - if you get over 10,000 the score readout can't cope and clocks back to 0.

[FrancoisLanciault]

Does it have joystick support ?

Regards

[Shaun_B]

Wee bug report, btw - if you get over 10,000 the score readout can't cope and clocks back to 0.

At least you get a chance at another extra life then?

I only get one extra life at 2000 points and have not made the score 'wrap around' yet, so good work

Regards,

Shaun.