Forums

I think I'm finished with my new game for the Game Gear. It's called Yum! Food is zooming towards your mouth. The object of the game is to open the mouth to let in pizza and cookies, and close the mouth for lettuce and broccoli. There are four different backgrounds, each one a level, until you get to level 5. Then the backgrounds keep changing but the levels don't increase. What do you think?

EDIT: I can't seem to attach the game. Help?

Trying again with attaching...

yumversion31.zip (17.37 KB)

Yum! (version 31)

It's funny and entertaining in a simplistic kind of way. I like it.

A little update could be "open / close the mouth" with the same button ;)

I see that you are not using all the graphical possibilities in terms of palette of the gamegear (errrr... on the cookie, yes), but it must be said that I have played more to this game than to some triple A of Steam.... Well done!

omg, why is this so much fun!?

Looks like you're not seeding your random sequences at all, so presumably it's possible to learn how to get really good at this game..

thanks for the feedback, all. I'll try to seed the randomness of the game.

It should be fairly random now.

By the way, I found this site which has a tiny RNG using LFSR, but it uses 6502 assembly and I don't know how to make it GG/SMS compliable.

https://codebase64.org/doku.php?id=base:small_fast_8-bit_prng Any help with that would be greatly appreciated.

yumversion32.zip (17.38 KB)

Yum! (version 32)

That’s a fairly bad RNG as its sequence is only 255 long. You can get better randomness easily on Z80, there’s a few algorithms around, for example https://www.smspower.org/Development/RandomNumberGenerator

Gamegearguy wrote

It should be fairly random now.

By the way, I found this site which has a tiny RNG using LFSR, but it uses 6502 assembly and I don't know how to make it GG/SMS compliable.

https://codebase64.org/doku.php?id=base:small_fast_8-bit_prng Any help with that would be greatly appreciated.

Yeah using a LFSR is a pretty good way to do it, the directly equivalent Z80 assembler for that example is something like this:

ld a, (seed) ; lda seed
sla a ; asl
jr nc, noEor ; bcc noEor
xor $1d ; eor #$1d
noEor:
ld (seed), a ; sta seed

The important thing is that you can start off with seed being different every game. There are a few ways to approach it, but you can certainly use the variable time it takes for the user to initially press the start button to set different seed values. Just note that you can never use 0 as a seed value because that will cause your LSFR to get stuck.

EDIT: sorry @Maxim saw I cross posted. Good point about the sequence length although I rather suspect in this game it would be unnoticeable.
I used a 16 bit LSFR to generate the scenery in Primates FWIW. Here's what I wrote in C, if that's of any use at all. Note that it right shifts rather than left:

uint16_t get_random(void)
{
static uint16_t random = 0x49E5; // initial static seed - so need to call get_random an arbitrary number of times to properly randomise
uint8_t lsb = random & 1;
random >>= 1;
if (lsb == 1)
random ^= 0xb400u;
return random;
}

Or to try and implement the same 8 bit left shift as your 6502 example (a bit contrived):

uint16_t tmp = seed << 1;
if (tmp & 0x0100)
tmp ^= 0x001du;
seed = tmp & 0x00ff;

Ive been using the Phantasy Star one, and it seems to work pretty good now that I added one to the RandomNumberGeneratorWord variable on each frame. I decided to add an extra one to it whenever the 1 or 2 button is pressed, so it should be even better now.
I also fixed a bug that didn't allow the broccoli to show up on level 1.

yumversion33.zip (17.38 KB)

Version 33

Gamegearguy wrote

Ive been using the Phantasy Star one, and it seems to work pretty good now that I added one to the RandomNumberGeneratorWord variable on each frame. I decided to add an extra one to it whenever the 1 or 2 button is pressed, so it should be even better now.
I also fixed a bug that didn't allow the broccoli to show up on level 1.

You shouldn't really need to keep on adding constant values to your seed throughout the game — in fact that might result in a "less random" sequence — once you have come up with a suitably random initial seed value right at the beginning of your game, you should be able to happily keep generating numbers just from the LSFR without worrying any more about it. But anyway, no point getting too scientific about it, with your sequences of vegetables as they are very little pseudo-randomness is needed to make the game suitably difficult so whatever works!

Anyone care to share a screenshot? )

Author	Message
Gamegearguy Joined: 06 Sep 2015 Posts: 268 Location: United States	Yum! (Game Gear game) Posted: Mon Sep 11, 2023 2:49 am
	I think I'm finished with my new game for the Game Gear. It's called Yum! Food is zooming towards your mouth. The object of the game is to open the mouth to let in pizza and cookies, and close the mouth for lettuce and broccoli. There are four different backgrounds, each one a level, until you get to level 5. Then the backgrounds keep changing but the levels don't increase. What do you think? EDIT: I can't seem to attach the game. Help?

Gamegearguy Joined: 06 Sep 2015 Posts: 268 Location: United States	Posted: Mon Sep 11, 2023 4:35 am
	Trying again with attaching... yumversion31.zip (17.37 KB) Yum! (version 31)

Kagesan Joined: 01 Feb 2014 Posts: 878	Posted: Mon Sep 11, 2023 2:52 pm
Kagesan Joined: 01 Feb 2014 Posts: 878	It's funny and entertaining in a simplistic kind of way. I like it.

ichigobankai Joined: 04 Jul 2010 Posts: 542 Location: Angers, France	Posted: Mon Sep 11, 2023 4:43 pm
	A little update could be "open / close the mouth" with the same button ;)

eruiz00 Joined: 28 Jan 2017 Posts: 556 Location: Málaga, Spain	Well done! Posted: Mon Sep 11, 2023 5:07 pm
	I see that you are not using all the graphical possibilities in terms of palette of the gamegear (errrr... on the cookie, yes), but it must be said that I have played more to this game than to some triple A of Steam.... Well done!

willbritton Joined: 06 Mar 2022 Posts: 671 Location: London, UK	Posted: Mon Sep 11, 2023 5:24 pm
	omg, why is this so much fun!? Looks like you're not seeding your random sequences at all, so presumably it's possible to learn how to get really good at this game..

Gamegearguy Joined: 06 Sep 2015 Posts: 268 Location: United States	Posted: Tue Sep 12, 2023 7:04 am
	thanks for the feedback, all. I'll try to seed the randomness of the game.

Gamegearguy Joined: 06 Sep 2015 Posts: 268 Location: United States	Posted: Tue Sep 12, 2023 7:48 am
	It should be fairly random now. By the way, I found this site which has a tiny RNG using LFSR, but it uses 6502 assembly and I don't know how to make it GG/SMS compliable. https://codebase64.org/doku.php?id=base:small_fast_8-bit_prng Any help with that would be greatly appreciated. yumversion32.zip (17.38 KB) Yum! (version 32)

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Tue Sep 12, 2023 8:09 am
	That’s a fairly bad RNG as its sequence is only 255 long. You can get better randomness easily on Z80, there’s a few algorithms around, for example https://www.smspower.org/Development/RandomNumberGenerator

willbritton Joined: 06 Mar 2022 Posts: 671 Location: London, UK	Posted: Tue Sep 12, 2023 8:12 am
	Gamegearguy wrote It should be fairly random now. By the way, I found this site which has a tiny RNG using LFSR, but it uses 6502 assembly and I don't know how to make it GG/SMS compliable. https://codebase64.org/doku.php?id=base:small_fast_8-bit_prng Any help with that would be greatly appreciated. Yeah using a LFSR is a pretty good way to do it, the directly equivalent Z80 assembler for that example is something like this: ld a, (seed) ; lda seed sla a ; asl jr nc, noEor ; bcc noEor xor $1d ; eor #$1d noEor: ld (seed), a ; sta seed The important thing is that you can start off with seed being different every game. There are a few ways to approach it, but you can certainly use the variable time it takes for the user to initially press the start button to set different seed values. Just note that you can never use 0 as a seed value because that will cause your LSFR to get stuck. EDIT: sorry @Maxim saw I cross posted. Good point about the sequence length although I rather suspect in this game it would be unnoticeable. I used a 16 bit LSFR to generate the scenery in Primates FWIW. Here's what I wrote in C, if that's of any use at all. Note that it right shifts rather than left: uint16_t get_random(void) { static uint16_t random = 0x49E5; // initial static seed - so need to call get_random an arbitrary number of times to properly randomise uint8_t lsb = random & 1; random >>= 1; if (lsb == 1) random ^= 0xb400u; return random; } Or to try and implement the same 8 bit left shift as your 6502 example (a bit contrived): uint16_t tmp = seed << 1; if (tmp & 0x0100) tmp ^= 0x001du; seed = tmp & 0x00ff;

Gamegearguy Joined: 06 Sep 2015 Posts: 268 Location: United States	Posted: Tue Sep 12, 2023 9:12 am
	Ive been using the Phantasy Star one, and it seems to work pretty good now that I added one to the RandomNumberGeneratorWord variable on each frame. I decided to add an extra one to it whenever the 1 or 2 button is pressed, so it should be even better now. I also fixed a bug that didn't allow the broccoli to show up on level 1. yumversion33.zip (17.38 KB) Version 33

willbritton Joined: 06 Mar 2022 Posts: 671 Location: London, UK	Posted: Tue Sep 12, 2023 9:28 am
	Gamegearguy wrote Ive been using the Phantasy Star one, and it seems to work pretty good now that I added one to the RandomNumberGeneratorWord variable on each frame. I decided to add an extra one to it whenever the 1 or 2 button is pressed, so it should be even better now. I also fixed a bug that didn't allow the broccoli to show up on level 1. You shouldn't really need to keep on adding constant values to your seed throughout the game — in fact that might result in a "less random" sequence — once you have come up with a suitably random initial seed value right at the beginning of your game, you should be able to happily keep generating numbers just from the LSFR without worrying any more about it. But anyway, no point getting too scientific about it, with your sequences of vegetables as they are very little pseudo-randomness is needed to make the game suitably difficult so whatever works!

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Sun Oct 01, 2023 9:28 am
	Anyone care to share a screenshot? )

Forums

View topic - Yum! (Game Gear game)