New game - Marine Fox

[cNp]

I 'like' the randomness... it's obviously doing something right that many games do in making me feel persecuted and starting to believe it's not random but there is code in there to make the sharks appear where the player is! I definitely need to take more care not to put myself at risk of random deaths! I should probably also read what the power ups do!

cNp

[mountaingoat]

I myself sometimes find thinking that the game is cheating and putting a shark right on top of me.

But I promise guys, it is just a random number. I think we are just more sensitive for when the shark shows up right above / below us.

Here is the actual code from the game, check it out:


...
 
; Add a shark at a random location - save the expensive random number
RAND_MACRO
sta tempB2

cmpa #110
blt no_more_sharks

anda #$7

ldx #bit_positions
lda a, x

; See if there is already a shark there
anda sharkOn
bne no_more_sharks

; Add a shark there
; Save back only the lower 3 bits for the shark X position
ldb tempB2
lda tempB2

anda #$7
sta tempB2

; Pick a random direction from a bit in the random
andb #$08
beq add_down_shark

...

bit_positions:
db 1, 2, 4, 8, 16, 32, 64, 128
First, we choose a random number that gets returned in 'a'. (I posted this simple macro in the programming section.)
We save it and only use it if it is a big number > 110. This way sharks don't show up right away after one is off the screen. Statistically it will take some time for a random number that big to get returned.

Granted this  check will skew the true uniform randomness but I think with this macro we already gave up on that. If we are to go through with the shark addition, pick the low 3 bits (0 - 7) and see if  there is already a shark in that lane, if yes, just get out. (sharkOn is a bit mask that indicates if there is a live shark on any of the 8 lanes and bit_positions is just an array for the nth bit as you can see.)

If no, save these bottom three bits for the X coordinate of the new shark and pick the next one for direction. If that one is '1' it is a "down_shark", otherwise it is an "up_shark" that comes from the bottom.

This is all. Notice how the code does not look at any coordinates from the player. So no cheating

[geoanas]

I have just flashed version 1.3 of "marine fox", having a quick play on my Vectrex...
It's been nearly two hours passed since and I am still playing...It' soooo amazing addictive!
My sons are fighting each other, who's gonna play next...ha!ha!ha!

Thumb up! You did it mountaingoat! You took me by surprise...I wasn't ready for this ! LOL ! ;-)
Thanks for this release !!

[mountaingoat]

Thanks for the kind comments, glad you and your sons like it!

[thomas]

Thanks for the 'Marine Fox' from me, too, I've played it a few times now on Vectrex hw and quite like it.
It's a vintage Vectrex game experience, although I also cursed those suddenly appearing sharks myself, too.
So here are two things I thought about while playing that would make the experience even better for me quite easily:
a) some simple 'attract mode' setup like the original games in-between the gameplay, a lot of the old games mostly display
something for a while (say the score and a 'got you humanoid' like berzerk) and jump to $f000 to restart which starts
the startup display/music again. If you push a button you sidestep this process again and immediately start a new game..
the Marine Fox simply stays at the 'Game Over' screen forever.. Would also prevent possible burn-in if the game would start
automatically after a while w/o pressing a button since it would switch eventually all the time
b) another game mode where the sharks would only appear after a basic vector arrow warns me shortly before they actually do appear
this one gives you at least a chance to avoid them if you are not too near to the edge..

I could live without b) but already thought about patching in a) myself (since it would be very easy..) so maybe it is something
you might consider…

[japjac]

mountaingoat-Congratulations on making a fantastic game and thank you very much indeed for doing so.

I love it and can honestly say it's in my top 10 for the format thus far.

Cheers.

[mountaingoat]

Thanks a lot guys.

I really like the idea of 'attract mode' I will probably add it.

[gliptitude]

Attract modes seem conspicuously lacking in Vectrex games. .. The few that i can think of really improve the overall presentation of the game.

[geoanas]

Total agree with gliptitude.

[Vectronic]

Yes, I do like attract mode in games. That sounds great for this.

[janzl]

Hi all,

New member here. I am sorry to bump this topic.

I recently bought a VecMulti cart. When I try to play Marinefox on it the screen turns either black or jumps back to the VecMulti's menu.

Am I doing something wrong? I have been reading this thread and it looks like everybody is able to play it.

Thanks!

[Vectronic]

Apr 5, 2016 15:45:18 GMT -5 janzl said:

Hi all,

New member here. I am sorry to bump this topic.

I recently bought a VecMulti cart. When I try to play Marinefox on it the screen turns either black or jumps back to the VecMulti's menu.

Am I doing something wrong? I have been reading this thread and it looks like everybody is able to play it.

Thanks!

I have this same problem on my VecMulti too with Version 1.3 - but I did not have a problem starting the game at all with version 1.0. I was hoping it would work for me on the next update, but it's been awhile and I forgot to ask about it.

[mountaingoat]

I don't have a Vecmulti unfortunately and I have never seen this with my multicarts.

Does anyone know what may cause this in general? My guess would be that the Vecmulti itself initializes something that does not seem to be compatible with the Marine Fox initialization.

[Mayhem]

Try seeing what patcher.exe says about the ROM, and whether it needs to be patched?

(the EXE should be on the SD card you got with the VecMulti)

[Vectronic]

Apr 6, 2016 6:09:00 GMT -5 Mayhem said:

Try seeing what patcher.exe says about the ROM, and whether it needs to be patched?

(the EXE should be on the SD card you got with the VecMulti)

I tried playing around with that utility, (I understand what it's supposed to do, but couldn't get it to work). Maybe I have to run it in DOS? No instructions on how to use it - also I won't be able to fiddle with it until much later on today. Much thanks to anyone for info regarding these things until I can get back home and try stuff out.