Got a bit of time and added player-bomb collision and player-alien proximity collision.
Added scoring and hi-score (until you quit) - game (1 life) restarts on death.
Added laser temperature gauge and overheat+cooldown.
Still get a warp per level and still have a stray crtc write that makes the screen jump occasionally!
122 bytes left!

Small update with fuel (timer)
Temporarily removed part of the fonts as I ran out of space; 135 bytes remaining.

Hi tricky,

are you already using pages 04xx-07xx and 0Axx-0Cxx?

Greetings
Kees

And some in between
I can save more bytes, but the big gaps are already filled.

added secotor number
added multiple ships per game
loosing a ship restarts the wave, but resets laser temp and fuel
fixed collision bug
removed SPACE to skip
it is almost a game (like AstroBlaster) now, still need to tidy some of the waves
64 bytes remaining

Just crammed page 2 and now have 247 bytes free, but docking/refueling is looking unlikely
I'm probably going to leave running out of fuel as loosing a life, not game over as in the arcades.
Any feedback, particularly what must be in or must not welcome.
Speech is out unless there is an extended (sw ram/B+/master etc) version.
I haven't looked in to the speech ROM expansion, but that may be an option!
I will add joystick support, probably same as Carnival(e).
I should be able to get the asteroids in and maybe a few secret bonuses.
I'm going to make the rocket levels single pass and tidy the formations that are currently just a flat overlapping row.
What sort of scores are people getting, I can usually get ~20k using one warp per sector.

The current version seems a little tight on timing for B-Em, and possibly some real beebs, so here is an update with the timing relaxed a little.

The previous version was a bit tricky to play on B-Em but this version is much smoother! Well done so far!

I managed to get to the level where the enemies go from left to right (on sector 2), descending every so often, before I ran out of lives. Sorry, I don't remember the score.

Don't worry
The hi-score is shown where player two's should be.
Adding a version without the dodgy crtc write, no jumping.
It also has an attract mode (well, at least 14 bytes of one)

It's looking good, impressive stuff!

A shame it's quite so tight for memory. It would be nice to have sound, and the full meteor stage. Would it save much to remove some of the later levels that mere mortals don't have much chance of reaching anyway?

Would be nice to have a Master enhanced version with everything, including the docking sequence

Good going on getting the game running so smoothly...

There should be enough memory to add the asteroids, which I was doing before I got distracted by sound and speech.

Sorry about the distraction. Still, it's sometimes good to get distracted.

I have to do sound eventually, it's just not my thing, the isn't a lot of optimization other than repeating parts of tunes, just a lot of fiddling to get the right notes in the right order or days trying to get an envelope that sounds right.

I know the feeling. It's one of the things I'm putting off doing for Castle Raider.

I've found a way that is a bit slow but is working for me for creating sound effects.
I can't "picture" what a sound wave looks like for a specific effect, so I find the effect I like (play lots of old games until I hear something I like) and then view the wave in WavePad, or any similar editor. Once I can see the waveform, I find it much easier to code. Often MAME will use a set of .wav files instead of emulating the sound chip and this makes grabbing them easier
For tunes, I try to find a midi file (not that easy) and then use the midi to csv... route that I described for Carnival. The other day I found .VGM (and .VGz/.VGM7z) files which are a collection of tunes from many old games (VGM is mainly SegaMasterSystem, but the sound chip is nearly identical to the BBC) which may give inspiration.

Just to let you know, I haven't given up, but have been struggling with sound a lot, again!
I now have the main sfx in except speech and refueling with 0 bytes left.
I am going to steal another row off the score / status panel to give me 1/2KB, which hopefully will be enough for the asteroids and some "secret bonuses".
If I stole a second line, it might be possible to get refueling in, but apart from completeness (which I guess may be worth it), that doesn't really gain much.
To add the stars will probably take another page, so they may be left out too.
As you might have guessed for me, this was about drawing more, bigger sprites at 50fps than any other game I know of (you may know better )
Richard
PS Some of the code that I have written for this will be very useful in Phoenix, although integrating it will take a while.

Here is a small update with sound, well, first pass at sound.
Also clawed back 47 whole bytes.
The sound in BeebEm is closest to what I was hoping for.
B-Em does a more accurate job of emulating the beeb.
Try it on a beeb if you have one handy.
Any feedback on sound is welcome.
Richard
Z,X,RETURN to fire and SHIFT for warp (once per sector/life only)
If you run out of fuel, you only loose a life, see how generous I am

Tried it on BeebEm as suggested and it sounds pretty damn fine to me for a first attempt at audio!

Both the player and enemy shooting sounds seem fine, especially on the faster levels (like the third set).

I can hear there's a quiet buzz whilst the various formations hover around, but it's so quiet I can't tell whether the pitch is progressively increasing (as in the arcade ver)?!?

The buzz at the start of level does if I remember correctly, but once in the level it doesn't.
Looking, or rather listening to Mame, there seem to be four different intro/background pairs.
Doing the full sound isn't going to be practical as the payers shoot, enemy shoot and some of the background beats take two channels each, as do the explosions if done correctly. I have compromised by having two channels for the player's and enemy shots allowing them to cut each other off, one for all explosions and one for the background beat. I do need to balance the volume, but with zero bytes available at the time, it was tricky. I think it is worth losing a row off the dashboard to add the asteroids, but not a second one for docking; I'm open to persuasion about that -I'll see how much memory some secret bonuses take.

Hi Tricky,

I just tested the version with sound, well done .... sounds great!!
This really takes you back to the 80's

Keep up the good work!

Greetings
Kees