Killer Heads of Lettuce (Channel F)

[+atari2600land]

I'm making a second game for the Channel F called "Killer Heads of Lettuce." It's sort of like a cross between Asteroids and Space Jockey. In the game, you shoot heads of lettuce in your spaceship. You can move the spaceship up and down, and I made a variable for lettuce speed and it seems to be working okay now. It's set to 1, but if I set it to 2, it goes faster. The object of the game is to keep the lettuce from reaching the far right of the screen. I'm still working on this game. You can shoot with the fire button, but the missiles can't shoot the lettuce because I haven't gotten that far yet. So, what do you think?

moving7.bin

[MemberAtarian]

I don't have any multicart for my Channel F, can you post a video about it?

[carlsson]

As far as I know, there is so far no cartridge that lets you load own ROMs. The multicart is great, but preprogrammed so emulation would be the primary way to test.

[carlsson]

Anyway, it is a good start. Will the lettuce blast into smaller pieces once the shooting is implemented, or be eliminated in its entirety? I wonder about the possibility of scrolling landscape with varying height, but then again you might need to find a way to detect on screen graphics that seemingly doesn't exist, or at least is not so easy to obtain. If you place the spaceship in the middle of the screen, you could allow it to change direction with some inertia like Defender. Hey, why not have little .. uh, cherry-men on the ground which you try to protect from the lettuce without killing the cherries, so it actually becomes a Defender inspired game?

[+atari2600land]

I was planning on making the lettuce be fully eliminated but then having a new one pop into place once that happened. I also have some code into place to speed up the lettuce, I just have to put code in to make it happen, which will be done at some point. I could do a video of what I have so far, but it would be of emulation, like the Kevin Vs. Tomatoes video I made.

[carlsson]

Sounds good. Consider ways to avoid the game getting too repetitive. For example the various waves in TSGWP added a lot to that game. Lettuce might appear at different speeds, different attack waves if possible. Perhaps lettuce that escapes to the right would consume part of the ground, until there is no land left? It would be fairly easy to keep track of how many lettuce have passed by and accordingly draw less land.

[+atari2600land]

I am busy adding some stuff to the game. For example, I added a way to make the lettuce heads move in a sinus wave. A variable determines whether it does or just moves in a straight line. The only trouble with this approach is that if the lettuce isn't shot and the player stands still, all it does is just go back and forth between sinus wave and straight. But what's the fun in that? And you're not supposed to do that anyway. I was going to have one life anyway (It would be easier to program.)

[TPR]

Yay! More love for the Fairchild!

[+atari2600land]

Back working on this again.

[+atari2600land]

I simplified the code. The game should (hopefully) work the same, but now with less code.

[+atari2600land]

Major update.

I added in lives, a life counter, and a song that plays when you lose a life. I also discovered that the game was not speeding up once 50 points was reached, so I fixed that. I wanted the life counter to be 1 digit, but it has to be 2 for some reason. Oh well.

moving17.bin

[+atari2600land]

Another major update. Added a lot of stuff to the game. Let me know what you think.

 

moving20.bin

[carlsson]

It plays well. I like that the lettuce has random speed and movement patterns. I don't know if there is are levels or objectives to the game just yet. Perhaps every 5 points or so, the red ship could advance to the left, making it harder to hit the lettuce but also increasing the score per hit. Or perhaps there could be something on top of the screen, like a cloud raining to stop your shots. I'm trying to not ask too much from this hardware, just variations to make the game a bit more complex.

 

Basically you now have four lives (3, 2, 1, 0) and you lose a life when the lettuce escapes. I still wonder if part of the ground could get removed each time a lettuce escapes, and the lifes are lost only in case you actually collide with the lettuce. It would make the game last a bit longer. Perhaps instead of moving the player to the left as I suggested above, every 10 times the lettuce is stopped, ground could reemerge up to the starting level. Anything to make it more complex and increase playability value.

[+atari2600land]

I have been having trouble determining when the lettuce collides with the ship. I need to check out two ISARS, and I need to know if one is greater than its value minus 3 and if the same one is less than the same value.plus 3. Then I would know the lettuce has collided with the ship. No levels yet.

[+atari2600land]

Well, I did it. It isn't pretty and it takes a lot of space to do, but the collision detection between ship and lettuce head is in the game now. The collision code sorely needs to be optimized, but I can't do it.

 

moving22.bin

[carlsson]

Nice! A very good improvement and something players would expect, that collision is detected. Too bad I can't help you with the code you posted in the other thread, at least not without spending a bit of time trying to understand the instruction set.

[+atari2600land]

I don't know if this will be able to play on a real Channel F since it's 3k, but here's the latest version. Someone really needs to make a Harmony cart for the Channel F.

 

moving23.bin

[+atari2600land]

Here's a version that SHOULD work. It is exactly 2,048 bytes. I had to change the songs a little bit to make it all fit.

moving23a.bin

[carlsson]

As I just commented in your blog, it appears to me that Channel F games may be up to 8K in size. Perhaps the larger ones require a different cartridge board with more complex chips, which only a true Channel F expert would be able to answer. So if you don't mind, for the moment being you probably can bloat a little instead of starting to trim features you want.

[+atari2600land]

As it turned out, and I noticed it, the game isn't 3k but it's 2.09k. The assembler always spat out binary files of exactly 2k (2,048 bytes). That is, until yesterday. I trimmed it down. Some had 2,045 bytes, some had 2,046 bytes. But you'd think anything below 2,048 bytes the game would automatically make it 2k. I just thought of something just now. I unremarked the org $ff0 part of the following code and it turned out to give me an exactly 2,048 byte ROM.

 

    org $ff0

signature:
    .byte    ".chris read 2018"

So I guess it's that org $ff0 statement that tells it to round up to 2,048 bytes. And as such, since it's 2k, I can't really add more to the game, so I guess unless someone spots a bug, I'll call it done? Unless in the meantime I figure out how to make an exactly 3k game or above. I've always noticed binary files to be exactly 2k or 4k or whatever, so I figured this needs to be the case for Channel F binaries as well, which is why I was concerned.

[carlsson]

I've gott 55 BIN files in my Channel F folder, divided as following:

• 41 files which are 2048 bytes each
• 4 files which are 3072 bytes each
• 1 file which is 3583 bytes (just shy of 3.5 kilobytes)
• 3 files which are 4096 bytes each
• 1 file which is 6144 bytes
• 5 files which are 8192 bytes each

Perhaps MESS doesn't mind BIN files of an odd length, but you are correct that in practise you want to pad files to a multiple of 1K or so.

 

I'll try your latest version later, though unless you get instructions you must not exceed 2048 bytes for it being practical to release in physical form if that is your long term goal, I still think adding is better than pruning if you're up for it.

[shantke]

How is this project coming along? Any more progress? I am looking forward to being finished!

[+atari2600land]

Last I knew e5frog was working on it, but he stopped e-mailing me with updates on it.

[siccoyote]

Quite fun, interesting how the enemies change their patterns, would be nice if you could adjust your shot, so they move up or down when you twist the joystick, to help get the more wild enemies.