Re: [stella] Have kernel, need game!

Subject: Re: [stella] Have kernel, need game!
From: Christopher Tumber <christophertumber@xxxxxxxxxx>
Date: Fri, 27 Jun 2003 20:55:16 -0400
I just remebered I was going to follow this up and never did. So here goes...

>The current kernel is quite simple and makes no difference between cave
>and not cave areas. Currently there are 69 cycles free, but I'll need
>about ~20 cycles if I want the top and bottom caves overlap (switching
>kernels!) and make the colors move when scrolling up and down.

You know, if you're switching kernals anyway - You could combine your kernal and "Mortal Kurling". Some levels would use your kernal, some would use mine. You levels would be more about piloting/dodging because of the speed (still with some shooting) while "Mortal Kurling" would be more about shooting.

Or, your kernal could be used all the time, except the "Mortal Kurling" episode would be used for Bosses.

Or whatever.

FWIW, "Mortal Kurling" is pretty simple, all it really does is:


Where PF is actually several Playfield bits. P0 and P1 are 3 copies, widest apart. If you position properly you get good, repetitive coverage of the screen.

Then P0 and P1 are scrolled 1 pixel every N frames (where N determines scroll speed), with a hard scroll of the Playfield and resetting of P0/P1 every 4th scroll.

Playfield is asymetrical (obviously) and P0/P1 are updated mid-scanline (And not that I have a solid idea how VDELPn works, I expect could be simplified since it currently has 2 kernals depending the vertical positions of P0/P1!!!)

Blank scanlines are there for the same reason in your kernal - To push data from ROM and avoid having to use a pile of RAM to hold all that scroll data (say, did someone mention a RAM cart?)

I wrote:

>> - Or a running game, say Lola Rennt, the video game. You're always
>> running foreward, to whatever goal (or being chased) so you can't slow
>> down. Only dodge (jump over? Say a top-dow view?) obstacles. Sorta a
>> horizontal Journey Escape (heh, heh).

Thomas replied:

>Sorry, but I don't understand how that idea fits to my current kernel.
>Can you explain that a bit more detailed, please?

Okay, picture a top-down view like umm Gauntlet or Frogger.

Yeah, actually picture a side-scrolling Frogger except much looser (not nearly so exact movements - more like Journey Escape) and much more variety of obstacles (Busses, cars, manholes, fire hydrants, dogs, cats, small children, &etc)

 _     B          
0_     C           

The area between the dotted lines is the active playfield (Player can move into the scroller to a limited extent depending upon the configuration of the walls but mostly will stay in the central playfield)
0_   Is the top down view of the player running (crude, I know)

D  Is a main obstacle created with P1, due to the vertical orientation you can do a
   fairly long vertical sprite 8x16 or 8x32 or 8x64 or even bigger...

X Is a minor obstacle created with M0/M0/Ball

Because of the speed of your scroll you should be able to get away with 1 main obstacle on screen at time and a couple minor (missile/ball) obstacles. If not, double or tripple copy the sprite and extend the sprite to the full height of the playfield. For example:

0       0       G
0       0       H
A       0       I
B       0       0 
C       0       0 
D       E       0 
0       F       0 
0       0       0 

Where A to I are sprite data, 0 is a blank sprite.

So ABC might be a bus, EF is a small car, GHI is a police car. Whatever...

Colliding with any obstacle kills you. You can dodge obstacles, also hitting the fire button causes you to jump. Jumping is represented by having the sprite get bigger as if you were jumping up - Use CTRLPF you double/quadruple sprite size (?). 

Doesn't have to be a running person, but you could really make that motif work. Put dotted/solid/paralell white/yellow lines horizontally through the middle of the playfield (with PF) like a street. Maybe sidewalks just before the scroller. Have the scroller represent buildings, so maybe a little more uniform to represent city blocks. Other obstacles could be mailboxes, lamp posts, parking meters, etc.

Then you could mix things up a little, say a level that takes place in a city park, so instead of a road you're running on grass. One scroller could be a river, the other bushes and you need to avoid streams, trees, small animals, golfers, &etc...


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