Lets Make a Retro Game - Episode 8 - Move and Shoot

This is the 8th video in my series, where I am going to work through the steps required to make a home brew game for a retro 8-bit console or computer system.

In each episode I will work through various topics, such as tools, methods and design.

All of the information referenced in each episode will have an associated article on my web site.

In this episode we are going to get some objects moving on the screen by:
- Testing the joystick direction and moving the player ship left or right
- Testing the joystick fire button and placing a bullet on screen
- Moving the current player bullet up the screen.
I have included the complete code for this section, so you can follow through the various steps without having to worry about typing in code.

The supplied code has two folders:
Start - where we start in this episode and
End - the final code and a copy of the ROM file.

The corresponding article with all download links and more detail on what is covered in this episode is available on my website here:

Next episode we will be going back to looking at our game and get some objects moving on the screen in response to input from the controls.

See general updates on both my web site:
and my Facebook page:

I also do live game plays, usually high score practices on Twitch here:

[BigGfromSA]

Great job Tony. I am planning on giving it a good go when I finally get some leave. Cheers

[TheHighlander]

Cool stuff. No need for keeping the sprite's coordinates in separate locations in memory.
I thought it might be a smart idea to test for button press AND release when getting from the title screen into the game. It prevents the game beginning with immediate fire.
I've been contemplating using characters as bullets and the mechanics involved in that. I wonder what your thoughts are on that.

[asktheprophet]

I am following your programming in assembler. Are you planning any more or in depth tutorials? You would get a lot of follower now the 'ZX Sprectrum Next' is coming out. A lot of people are interested in coding for it.

[lilacfloyd]

Great video as usual.
Keep up the good work. :)

[richwalter]

Have you tried this on real H/W? I noticed on startup there are extraneous patches of sprites showing up, hitting reset clears them. But after going into the game screen from the title screen, if you hit reset, the player ship still appears on the title screen where it was on the previous screen. I don't see that behavior under blueMSX though. Something not being initialized/cleared properly maybe? I don't have any issues with other ROMs (so it's not the dirty power switch glitch).

[colwarsstudiobrickfilmandm]

now im working on my own project but i cant figure out how i would use the y position for movement any ideas?

[Jescribano]

One noob question. Im using this as material for a project and got here looking for a way to move my avatar. Problem is the teacher wants the player to move using the "O" and "P" keys as imputs. Can someone give me a hand with that? Cause i cant find the JOYDIR routine in the source code

[ThePaulLondoner]

How and when did this suddenly change from MSX code into Colecovision code? It's enough to try learning Z80 Assembler without switching between MSX and Colecovision. Please stick with MSX code in future! I hope your next instalment in this series will be soon and just about MSX.

[BigGfromSA]

Damn, it would be great if you could learn programming like they do training in the Matrix movie. Just download the knowledge straight into the brain. Then I may stand a chance to actually become a programmer. LOL