Space Invaders / Connect-4

[beamrider]

Yes, a great job on this
agree with everything highinfidelity said...

If you're nit-picking I think the time taken for a bullet to traverse the full screen vertically is perhaps 25-20% more than the arcade. i.e. the arcade took about 100 frames but the Vic version about 130 frames when I compared on recorded video. (It was difficult to get exact measurements so double check this before spending much time on it.)

[Lechuck]

Hi Highinfidelity,

Being a *huge* Space Invaders fanatic (all times' best game in my opinion - despite its simplicity) this is great news indeed! If you're currently upgrading it to 8K RAM, you may have already addressed these points, however here they are...

- when the player sweeps the "base" across the screen and shoots at the same time, the base halts, shoots, and then begins to move again after a while. To be honest I didn't have time to re-check this on the arcade game, but I'm nearly sure that the base keeps going as you shoot "on the fly".

Yes, you are right. Have just checked the original one in MAME, and it is true that shooting doesn’t ‘stop’ our base. I think this is caused by the way I check keyboard/joystick. I include some delay to avoid moving too fast but firing shouldn’t initialize that delay. I have to check but I think I should be able to fix that.

- the "mother ship" at the top of the screen moves in a very blocky way (don't know if anything can be actually done about this) but most of all definitely moves too fast. In the arcade game, when the "mother ship" appears, it moves deliberately slow and you can easily reach its perpendicular even if you're running after it coming from the same direction. I suppose the idea is that it has to "tempt you" to go for it, and then being killed while you loose control of the rest of game (which happens to me quite frequently, I have to admit ). In your 3K conversion you either hit it by mere chance, otherwise there are almost no chances to effectively pursue it: you just let it go, which I believe doesn't convey the spirit of this detail of the game.

Yes, that is true. Mother ship moves too fast, what ‘kills’ the idea of using the mother ship to make us to leave a ‘covered’ position, and this is caused because the mother ship movement is 'blocky’. As you have found, mother ship movement is at 'char level'. Mother ship was the last addition to the game I did, and, by then, I was already strugling with the available RAM, so decided to ‘simplify’ it (using char level instead of bit level movement). To avoid this char level movement to be too evident, I made it to move very fast (moving slow at char level made it too ‘flickering’). Now, with 8k, I should be able to move the mother ship at bit level and, so, make it to move slower. Will give it a try before uploading the new version.

- you have written that you are are already reviewing the sound effects, so the following may be outdated already, however... I truly appreciate the way in which you tried to deliver an arcade-grade "shoot" sound of the missiles - no other programmer that I know ever even cared to get remotely close to it. That's really great! However, at least judging by the speaker of my monitor, the pitch is so high I seem to be barely able to hear the sound. Perhaps the effect would sound better, should the pitch be lowered slightly, but really very slightly. Also, there is room for improvements in the sound of the "mother ship" when it crosses the screen, but again I ignore if touching the mother ship routine is feasible at all without messing up the rest of the game.

Yes, sound effects, plus the option of playing two players mode are the main changes in the new version (and I’m particularly proud with the result of the new sound effect of the mother ship that, in the previous version was terrible ). Regarding sound for our shooting, agree with you that sometimes is hard to listen (you are probably right and it is too 'high'). I hadn’t modified that one in the new version but will follow your suggestion of slightly lowering the pitch to see the result).

Thank you once again for all the work that went into this, I agree with all other posters that this is by far the best attempt ever made to deliver an arcade-correct conversion of Space Invaders! Thumbs up!!!

Thanks to you for your feedback and the detailed analysis and suggestions. Really appreciate them!. I hope to be able to upload the new version soon. I'll try to include all your suggestions (if I’m able to implement them )

I’m also a big Space Invaders fan, so it is great to try to improve my version with the feedback I get here.

Cheers

[Lechuck]

Hi Beamrider,

Yes, a great job on this
agree with everything highinfidelity said...

If you're nit-picking I think the time taken for a bullet to traverse the full screen vertically is perhaps 25-20% more than the arcade. i.e. the arcade took about 100 frames but the Vic version about 130 frames when I compared on recorded video. (It was difficult to get exact measurements so double check this before spending much time on it.)

Thanks for the suggestion. To adapt speed in the game I was using a chronometer what is not, probably, the most accurate option . Recording a video and comparing it with the Arcade should allow me to better fine tune the speed. Will check and adjust where required.

Cheers

[highinfidelity]

Thanks a lot for taking in consideration what I have written! Can't wait to try out the new improved 8K version!

The missiles' speed is a tricky point, as the screen ratio of the arcade and the VIC is radically different, almost 90° rotated. So it's really hard to tell, but as a "general feeling" felt while playing, I also had the overall impression that the missiles were moving a bit on the slow side.

[Lechuck]

New 8k version uploaded to the original thread:

viewtopic.php?f=15&t=9974&start=15#p113397

I have tried to follow suggestions from Highinfidelity and Beamrider. Besides that, this version provides 1P / 2P modes, new fonts, better sound effects (I think ), and some other minor changes to better mimic the original arcade.

Cheers

[highinfidelity]

WOW thanks! Can't wait to try it out!

[nbla000]

New 8k version uploaded to the original thread:

viewtopic.php?f=15&t=9974&start=15#p113397

I have tried to follow suggestions from Highinfidelity and Beamrider. Besides that, this version provides 1P / 2P modes, new fonts, better sound effects (I think ), and some other minor changes to better mimic the original arcade.

Cheers

I've briefly checked your very good 8k version on VICE, I've seen that you may use cursor keys to center screen but I think is better you propose a best value for each system by looking on $EDE4 location, it reports $05 for NTSC machine, $0C for PAL machines, best value for 9000 9001 on NTSC seems 03 13 at least in emulation.

[beamrider]

Perhaps use the best value for the initial position, but keep the cursor centering please?

On a real CRT lots of things affect the position.

[Lechuck]

I've briefly checked your very good 8k version on VICE, I've seen that you may use cursor keys to center screen but I think is better you propose a best value for each system by looking on $EDE4 location, it reports $05 for NTSC machine, $0C for PAL machines, best value for 9000 9001 on NTSC seems 03 13 at least in emulation.

Hi Nbla000,

Thanks for the info. Yes, sure, much better. I’ll set the proper values for 9000 and 9001 depending on what I get from $EDE4. Will include it in the next version I upload.

Cheers

[Lechuck]

Perhaps use the best value for the initial position, but keep the cursor centering please?

On a real CRT lots of things affect the position.

Yes, sure, will just change initial values but keep the option of centering with the cursor keys.

Cheers

[beamrider]

Will have a look later, but first impressions is it looks fantastic, best version of invaders I think I've played on ANY 80s computer.

There's a slight tweak you could perhaps make. On the original when the player missile gets to the top of the screen without hitting anything, it very briefly turns into a red explosion for maybe 1/3 second before disappearing.

[Lechuck]

Will have a look later, but first impressions is it looks fantastic, best version of invaders I think I've played on ANY 80s computer.

Thanks a lot!. It’s very kind of you. I’m glad you liked this new version.

There's a slight tweak you could perhaps make. On the original when the player missile gets to the top of the screen without hitting anything, it very briefly turns into a red explosion for maybe 1/3 second before disappearing.

Yes it is true. In the original arcade, when our shooting (or Invaders missiles) reach the end of screen, there is an explosion effect. Replicating that should’t be dificult but special care needs to be taken when it happens close to the mother ship or near our base. Both are three characters wide so it can happen they weren’t hit by the missile but cannot simply replace the full character because that would be hidding part of the ship / base (so, combining chars, as in other parts of the game, will be required). Something to think about, for sure, for next version (That will allow me to keep enjoying improving the game )

Cheers

[highinfidelity]

I have to agree in full with the above: this is by far the all times' best port (and not emulation!) of Space Invaders I've seen on any classic system! Standing ovation!

The gameplay is indeed excellent, and you did a terrific work with the mother ship! I only have the impression that it comes out too seldom, but it's just an impression, I may be wrong... I have the feeling that it comes out more often on the arcade, but actually I've never went in-depth about the logic with which it appears, or chronometered its timing etc.

The base shots' speed seems absolutely "spot on" to me now. On the other hand, I have the "feeling" that the invader's shot travel a bit too fast - but I also have to say that I didn't experience dying too many times or too quickly, so again it may very well be just a wrong impression.

The sound of the explosions is really remarkable. The sound of the traveling missiles is in turn amazing (more hearable now!) but I wonder if there's still room for some refinement... How is it done? Is it the mix of a tone and white noise? In case, perhaps you could try to change the mix a bit and enhance the white noise over the tone. Also, if feasible at all, perhaps you could try to progressively lower the volume a bit while the missile crosses the screen.

These are of course all lesser details in a game which is absolutely remarkable and enjoyable as it is!

In a rainy sunday you may also think about improving the startup screen a bit. I believe that now the alien that inverts the "Y" moves at character level; it would look much finer should it move at pixel level. Then perhaps - without going as far as to program a true "attract mode" - you may think to simply erase the screen after some delay, and repeat the whole sequence of writing the instructions line-by-line, followed by the inverted "Y" gag.

Again *THANK YOU SO MUCH* for all the work that went into this - my goodness I have waited for this literally for 40 years!!!

[orion70]

I'll never thank you enough for this, Lechuck. This adds immensely to my retro experience

[Lechuck]

I have to agree in full with the above: this is by far the all times' best port (and not emulation!) of Space Invaders I've seen on any classic system! Standing ovation!

Thanks a lot!. I feel overwhelmed.

The gameplay is indeed excellent, and you did a terrific work with the mother ship! I only have the impression that it comes out too seldom, but it's just an impression, I may be wrong... I have the feeling that it comes out more often on the arcade, but actually I've never went in-depth about the logic with which it appears, or chronometered its timing etc.

You are probably right. Being random it is dificult to identify a pattern in the original to mimic it. In fact I got the impression, in the previous version, that it was too frequent, so I reduced it to one half. Will check it again

The base shots' speed seems absolutely "spot on" to me now. On the other hand, I have the "feeling" that the invader's shot travel a bit too fast - but I also have to say that I didn't experience dying too many times or too quickly, so again it may very well be just a wrong impression.

I’ve been playing with speed of both shootings and yes, it is very likely invader’s one is now too fast. As you mentioned in a previous post, given the difference in the vertical size between the Arcade and the Vic, it is dificult to find the best value. But this is easy to change so I’ll try to fine tune it

The sound of the explosions is really remarkable. The sound of the traveling missiles is in turn amazing (more hearable now!) but I wonder if there's still room for some refinement... How is it done? Is it the mix of a tone and white noise? In case, perhaps you could try to change the mix a bit and enhance the white noise over the tone. Also, if feasible at all, perhaps you could try to progressively lower the volume a bit while the missile crosses the screen.

Funny you ask. By now I don’t use the white noise for it but I found, listening again to the original, that it might be a good improvement so I was considering it (by now, for this sound, I am using just one of the voices-the third one-, changing the pitch up and down) Mixing more than one voice for one sound effect will require some changes to my sound subroutine, but I was planning to give it a try. What I cannot do is to play with the volume since it is common with the rest of the voices so that would affect rest of sound effects.

These are of course all lesser details in a game which is absolutely remarkable and enjoyable as it is!

In a rainy sunday you may also think about improving the startup screen a bit. I believe that now the alien that inverts the "Y" moves at character level; it would look much finer should it move at pixel level. Then perhaps - without going as far as to program a true "attract mode" - you may think to simply erase the screen after some delay, and repeat the whole sequence of writing the instructions line-by-line, followed by the inverted "Y" gag.

Playing the presentation screen in a loop is a good idea (and simple to implement). Making the allien in this screen to move at bit level shouldn’t be dificult either (I thought nobody would realize that ). Added to the list for a future version.

Again *THANK YOU SO MUCH* for all the work that went into this - my goodness I have waited for this literally for 40 years!!!

Thanks to you for all your kind feedback and suggestions. I really enjoyed programing it and keep enjoying improving it. It is very encouraging to know there are other people playing it!

Cheers