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Gaxian wip


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  • 1 year later...
9 hours ago, artrag said:

I have resurrected the project and successfully ripped away all the jpl extensions and now the game works fine in a standard cartridge with the standard ram...


Keep in mind that most modern "standard cartridges" do support extended 16-bit RAM at the 8K range.  What they do not support is the JPL extensions for accelerator functions and non-volatile (Flash) RAM.



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Do not worry. ATM the game is using 46 out of 47 words in ram and I do not think I will need more than that.

I am implementing the collisions for enemies in charge mode, and for that no extra ram is needed.

There could be some need of ram while implementing swarm attacks by the yellow ships and their minions, where the scoring system is a bit tricky, but I think I can use the 8 bit ram for that.


For your fun the current WIP


Galaxian.cfg Galaxian.bin

Edited by artrag
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1 minute ago, artrag said:

Now collisions should be complete. I've also changed the way the main ship casts bullets.

This could be the last release for a while, till to the complete game...


Galaxian.cfg 343 B · 1 download Galaxian.bin 22.05 kB · 1 download

I haven't had a chance to try the binaries yet, but I hope to get some time with it this week-end.  I am very excited over this game. :)



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Hi, @artrag,


I gave the demo game a chance this morning and I have some feedback, which I hope will help improve the game.  First, let me start by saying that it is quite impressive.  It's not perfect and needs some work -- but it definitely looks, sounds, and feels like Galaxian.  And the fact that it grapples with some measure of success the severe limitations of the Intellivision, it is quite an accomplishment.  So, please, take it as high praise.


That said, below are some comments on the game as it currently stands:

  • The sound effects are brilliant!
    Very close and definitely reminiscent of the original arcade.  I would only recommend balancing the volumes between the player shot and the enemy-in-flight attack.  The screeching sound the enemies make when leaving the formation to attack seems a bit muted.  I find this sound (which I think you've reproduced faithfully) to be one of the key features of Galaxian -- not only are they unique and instantly recognizable, but it also helps to alert the player that a new enemy is on the warpath.
  • The enemies are all a bit generic.
    I know that it's hard to reproduce the 16x16 pixel, multicolor style of the arcade, but I wonder if they could at least be made to look a bit closer to the original.  The chosen colours work very well and match the arcade, so that helps.
  • The score and flags take precious vertical space for limited gain.
    Don't get me wrong, the screen looks fabulous with the HUD present, and in some sense I feel it would be a shame to get rid of it.  However, I wonder if sacrificing it would improve game-play by providing a larger play-field.  You can always show the score and the lives in a "Pause" screen (if you include one), or in the interstitials between levels.  Then again, it's a single row, so it may not do much to game-play anyway.  Still, it may be something worth exploring.
  • The explosion frame-rate is much too slow, it also needs some red in it.
    From the looks and layout, I will guess that the MOBs are reserved for the attacking enemies and that everything else is rendered as a background card.  If so, I can appreciate why the explosion is monochromatic.  Nonetheless, if you could speed up the animation, you could flash a bit of red on it by either multiplexing or just by alternating between red and white stages of the explosion.  The animation speed may be a limiting factor due to the number of tasks the game must perform.  I won't pretend to know how you developed the game code (since I know you are much more capable in mathematics and algorithms than I am), but if the code is in IntyBASIC, maybe some routines could be hand-optimized in Assembly Language -- especially since you removed the dependency on JLP accelerators.  I am willing to assist in any way I can, should you be interested.
  • Collisions seem a bit ... iffy.
    I understand that managing object interaction between MOBs and background cards, object multiplexing, and a multi-frame pipeline, can all affect the way collisions are handled -- but as it stands right now bullet/enemy, bullet/player, and even enemy/player collisions are very flaky.  I suppose you are not using hardware collisions, so perhaps the bounding box calculations are a bit off, or maybe they run too late in the pipeline and are missed.  In the interest of useful feedback, I offer the following observations related to collisions:
    • Enemies in the top formation are killed as soon as a bullet reaches them, irrespective of the horizontal orientation of the bullet with respect to the enemy.  This seems like the correct and expected behaviour.
    • Player bullets tend to kill enemies when they reach the dead-center of the enemy sprite, and sometimes they miss altogether.
    • Enemy bullets appear to be more accurate (at least it seems I always die when they touch me).
    • Player and enemy sprites can overlap somewhat, and only appear to register a collision when touching the center of one or the other, and sometimes not at all.
    • The yellow enemies are the hardest to kill.  For some reason, bullets mostly go through them.
  • Player sprite is a little jerky.
    The enemy sprites move rather smoothly, but the player sprite seems like it stutters as it moves.  This could be due to the speed scaling, but maybe it can be smoothed out a little.
  • Animations are a little glitchy.
    Sometimes, when an enemy sprite transitions from the formation into attack mode, the sprite flickers with garbage or a different frame.  Also, when an enemy sprite is at an angle, it seems to flicker between two different orientation frames, perhaps due to rounding between two discrete angles.  The enemy explosions also seem to twitch between two horizontally adjacent cards.  I think this happens when the enemy is killed right when he is about to transition to a new card.
  • The difficulty balance seems about right, with the enemy flight patterns and speed scaled down due to the limited vertical space on the play-field.  Perhaps some minor tweaking is in order once the rest of the levels are added, but I found it fun and engaging.

That is it for now.  I hope this proves useful.  I really like how the game is coming along, and I'm sure that once the additional music, interstitials, levels, and other final elements are added and polished, this one is going to be a great addition to the Intellivision canon.



Edited by DZ-Jay
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  • 5 months later...
9 minutes ago, artrag said:

Now in PRGE 2022


Wow, Arturo, I have to say that, even though I've seen the demo during development, the final version is even more impressive.  This game looks fantastic, and I can't wait to get a copy!


Great job, and congratulations on another release.  I'm sure that Galaxian will be a flagship title of the Intellivision canon. 👍



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