Galaga C64 (Preview 1)

Preview 

This is a preview version so that I can gather feedback on how it feels compared to the arcade, how much interest there is (the final version will be free of course) and some bug reports while I take a little break from it. There are debug symbols in the right panel so any screenshots or videos of bugs can be put into some context.  NSTC version may be a bit more flickery, no point optimizing that until all the timings are finalized, it will also play a lot faster, but I will have separate lookup tables for speed in the final version.

- Background

This is one of my all-time favourite games, if ever I've got 5 or 10 minutes spare for a game I will always choose Galaga. So I thought it would be nice to be able to play it on my favourite machine. 

One obstacle of a decent Galaga port is the C64's aspect ratio, with the screen just 200 pixels tall compared to the Arcade's 288 pixels. However, the highly-rated NES conversion managed to squeeze it into 224 pixels, so all I needed to do was open up the top and bottom borders for sprites and use 12 or more pixels in each to make up the difference.  

Another big hurdle is the sheer number of sprites. Having looked at the NES version more closely I noticed that the formation doesn't move smoothly like it does in the arcade. So I decided that if enemies were drawn using characters when in formation, and sprites used elsewhere, there would be plenty of sprites available using a slightly modified version of Shallan's multiplexor. I don't think it detracts from the gameplay too much, as the main action is concerned with spawning and diving enemies anyway.

- What's still to be done?

• Ability to shoot your captured fighter when in flight. 
• Ensure an orphaned fighter (its boss was destroyed while in formation) can dive on its own and leave the level (Currently you'll need to shoot it in formation to progress).
• Orphaned fighters re-appear on next level as part of the final wave and take their place in formation again above the first available boss.
• Music and some missing SFX
• Transform enemies that spawn from a formation enemy and have unique patterns.
• Challenging stages 4-8. Currently 1-3 will repeat.
• Two-player mode
• Improve dive attack movement of butterflies, currently too erratic
• Prevent captured ship from being hit by enemy bombs

If anyone would like to help in anyway, whether that be doing the music in Goattracker, working out the patterns for the remaining challenging stages or getting involved with bug fixes, please get in touch! 

Thanks to Stefan Wessels for sharing the code to his modern remake of the arcade version, which I have used as a reference for certain bits of the code, and also converted the wave pattern data to a C64-friendly format.

Galaga in AppGameKit