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spiffy saucer & UFO

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  • New saucer and UFO graphics
  • new medium asteroids using 24 frames of rotation (so it matches the large asteroids)
  • Ships accelerate faster than before
  • Ships have more inertia
  • speed of asteroids increased. The prior sixteen speeds were 3 -> 9 in steps of .4, they're now 5 -> 11 in steps of .4
  • rebuilt the shot offset tables so shots now start at the ship's nose instead of in the middle of the ship
  • revised the vertical wrap-around logic. Before all objects would wrap using an offscreen zone size of 32. This was so the large asteroids would fully move offscreen before showing up on the other size. Now they wrap based on the size of the object
    • 32 = large asteroids
    • 16 = medium asteroids, ships
    • 8 = small asteroids, UFO

    [*]Right Difficulty = A unlimited lives. The remaining lives digits will be used to display the current level number in hex, as shown in the screenshots below. Computers start counting at 0, so the first level is 00. This was added for performance testing on the Harmony1 to make sure I'm not running out of processing time in later levels.

Level 1 (hex 00 + 1)



Level 11 (hex 0A + 1)



Level 16 (hex 0F + 1)



Level 17 (hex 10 + 1)




ROMs for Harmony or Stella 3.7.1 or later







1 Performance testing must be done on the Harmony because Stella doesn't emulation ARM cycle time.


Performance testing looks good so far.


Rubber bands so I can do other things during the test.



Level 62


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Got up to level 104 then lost power :(


Wonder if that had anything to do with it being 102F outside :ponder:

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Yeah, that's still on my to-do list. I need to rearrange memory usage as I'm just about out of space in the ARM section of the ROM. Until it's in place you can just hit GAME SELECT to go back to the main menu to see your score from the prior game.


I wasn't planning on a new build this soon after the last one, but Nathan's new graphics were too nice to hold back so I took a break from the 32 character stuff and dropped them in. While I was at it I did a few easy changes that wouldn't increase code size:


Speed tables are controlled by 2 cells in an Open Office spreadsheet. Modify those then copy/paste the recalculated data and the speeds are changed.


Ship physics are controlled by a couple constants in the defines.h file.

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This keeps getting better.. love the new ufo design!


I also like how when I get hit by enemy fire from UFOs, my next ship respawns while the UFO is still on screen, giving me another chance to take revenge on the bandit! Unlike the atari version that forced you to wait until the UFO left the screen and made it's escape.


One thing that does bother me in this build however is discovering when I enter into hyperspace after thrusting, my ship continues it's momentrum when I come out of hyperspace. At first I thouhght "Cool!" But then I often get killed because I don't catch where my ship is at in time before colliding with a rock.

Might have been cool if I can activate my shield to avoid that kind of wipe out, but that's not available together with hyperspace.

I think it's best to have the ship come out of hyperspace in standing position instead.

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Maybe that could be part of the difficulty settings. Easy = momentum canceled during hyperspace jumps, difficult = momentum maintained.

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Hmm, possibly.


I'm thinking about having LEVEL (difficulty) also control the initial asteroid count: Kids = 2, Easy = 3, Normal = 4, Hard = 5. The count would still increase by 1 after each wave is cleared.


Maybe tie it into the FRICTION option. If friction is enabled then momentum gets zeroed. If friction is disabled then momentum is maintained.

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The ship acceleration feels perfect now. The game looks really nice - the large high-rez rotating sprites are very different for the 2600 (even with ARM assistance).


My only complaint now is that the ship explosion looks a bit weak - is there any space for a better effect?


I really hope you finish this one and don't get distracted :)




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The explosions are still my handiwork, I'm sure Nathan will get to them in time :)


My goal is to finish Space Rocks by the end of next month. I'll take a break in August. In September work will resume on Chun-Li. I'll take another break at the start of the year, then return to Frantic.

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Ship exhaust is next on the list (in-progess), then things go boom. Espire8 has sent some nice-looking explosions, which I'll use as a starting point.

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Space Rocks looks and plays great! This game is addicting and I hope to see it available on a cartridge. Excellent work! :)

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I did liked the continued momentum at first because it was radicaly different. Sort of adds to the risk of using hyperspace too often as a cheating technique as is often done in the arcade version, but that feature may not be for everybody.

But the idea of tying it in as an option along with the FRICTION selection sounds awesome!


One other solution came to my mind that may help reduce the chance of a wipe out while keeping the momentum in there is having the ship re-materialize when coming out of hyperspace. Like the way it's done for the ship in Defender, using a reversed animated explosion converging to where the ship will reappear for about 1 second before it comes out of hypersdpace with continued momentum. That may help players spot their ship in time to take evasive action to avoid collision with an asteriod.

Sort of adds to the intensity of that "narrow escape" adrenilin which I think would be way cool!

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I made the following changes while rearranging memory usage yesterday. They'll be posted when the next graphic updates are dropped in.

  • hyperspace momentum is now tied into FRICTION.
  • initial asteroid count now tied to LEVEL.
  • 2 second delay after final death before displaying menu.

I've debated temporary immunity after hyperspace, it'd be just like respawn (so the luminance cycle would get reused) but for just 1 second instead of 2. Not sure if I'll do it or not. In Asteroids you always had a risk of losing your ship when coming out of hyperspace - even if you didn't appear in front of an asteroid. While I can understand getting killed because you reappeared in front of an asteroid, I never liked getting killed "just because" so I dropped that in Space Rocks.

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This version has turned the fun level up a notch ... I like it!


I wanted to report something unexpected that I experienced using Light Sixer+Harmony. On my very 1st game (1P/Solid/Normal/Shield) I blasted all of the asteroids without noticing a single saucer and then waited a while (maybe 30s) but a new wave of asteroids failed to appear. I hit Reset and selected the Hard level and all games from that point worked flawlessly (and I got to see the new saucer/UFO graphics).

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Hmm - by chance were the asteroids stationary? There's a testing tool in place where setting Left Difficulty to A will freeze the objects so we can review the graphics and make sure I converted them correctly. When frozen, the saucer won't come out, and the next round won't start.

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I checked my Left Difficulty - it was positioned halfway between A and B and I notice it seems loose. We had a bunch of toddlers over on the weekend and my girlfriend did mention she had to put my Atari away...


Anyway, you must be right - that 1st game must have been played on A. My theory is when I hit the Select switch to change game options, the slight jar+gravity must have been just enough for the finicky switch to toggle from A to B, thus taking the game out of test mode from that point on. Thanks.

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Been playing this a lot without friction option and tried using the classic cheat of leaving one asteriod on screen and just constantly thrust while picking off ufos. It works for the most part and I love the continued momentum.

Just to note that the player ship's top speed is not as fast as arcade asteriods. I think the arcade's top speed is about double what space rocks is currently. I also think using invulnerability for 1 sec after hypersace will make it too easy for the cheating technique and if a player were to constantly hyperspace.


I also like how the player's next ship can respawn in different areas instead of only dead center. In FIGHT mode, that will keep the rival player (and respawning player) guessing where it may appear without the other player tying to snipe a shot by firing towards the center during a respawn.

The best way I feel hyperspace respawn were handled was in Vectrec's built-in Mine Storm game.

The reverse explosion affect was very good eye candy as well as helping the player see for 1 sec where the ship will reappear while being immune and not able to control the ship until it fully rematerialized. Too bad no continued momentum were present, but Space rocks may have an opprotunity to build on that idea. Worth a thought maybe.

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In arcade Asteroids, after people started "lurking" for UFOs, Atari changed the game to prevent it. You could no longer hide behind the score, and the UFO would target the last remaining rock(s).


They further addressed this in Asteroids Deluxe by bringing out the Killer Satellites when you were down to three rocks left.

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Maximum speed could be increased, though the shot speed will need to be increased as well otherwise your ship would be able to outfly your shots.


I was down to $90 (144 bytes) of space for ARM code, so at the moment I'm working on making space for additional code. Until that's done, I don't know what new features will be possible. Having the ship luminance cycle for a second, with the joystick input disabled, would be an inexpensive way to come out of hyperspace.


I suspect that the planned tether option is going to get dropped.

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