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can this awesome River Raid hack work on the real game?


ComputerSpaceFan
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I just discovered this awesome version of River Raid on iTunes which has a unique version called Fantasy mode (skip to the 7:40 mark to see it). I was wondering can such a mod be done to the original River Raid ROM so this version is playable on original hardware? It's tons of fun!

 

https://www.youtube.com/watch?v=8S8flHTy8wc

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Yes...flicker the player's missile at 20hz. If all 3 missiles are to disappear when any one of them has hit something, such a hack wouldn't even require additional resources (though there are a couple of bytes of ram unused in the original game).

 

Ohh baby!

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Not bankswitching...just drawing the missile at skewed positions for 2 frames.

 

Example:

 

; x-position missile:
       INX                      ; 2
;;       LDA    missileX          ; 3
       LDA    frameCnt          ; 3
       LSR                      ; 2
       AND    #$01              ; 2
       BCC    Straight          ; 2
       BEQ    NoLeft            ; 2
       CLC                      ; 2
       ADC    zero2             ; 3
       .byte $2C                ; 4
NoLeft:
       SBC    zero2             ; 3
Straight:
       CLC                      ; 2
       ADC    missileX          ; 3

 

.skipJet0:
;;       LDX    zero2             ; 3             load 0 with exactly 3 cycles
       LDX    zero1             ; 3             changed variable

 

; *** move or fire missiles: ***
       LDA    missileFlag       ; 3
       BPL    .noMissile        ; 2
;added line
       INC    zero2             ; 5
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Damn...it's difficult to find some space here. !!!!!! game killer removed. Supercharger-compatable.

 

I wonder if the 3 shots could be added to any of these hacks:

 

atariage.com/forums/topic/220544-river-raid-turbo-wrandom-start-and-other-river-raid-hacks/

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Not really. Although the score table is set up to record zero points for hitting a house, the chances of doing so are n/a (a missile would hit the playfield before it reaches a house). Flickering the missile means that they can reach farther inland than normal.

 

On that subject, I fixed the flicker for 20hz (the binary above does the center missile twice in 2 frames). Now each one only appears once in 3 frames. The !!!!!! freeze is back in place, too.

RiverRaid(Fantasy_Mode_V2).bin

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Working on a smoother version that uses 30hz flicker of the other missile sprite for the side shots (and leaves the center shot unflickered)...but I ran into a slight problem where roads are (M1 would be doubled on roads). May not be a big issue, since the bridge is the only thing hittable on those scanlines...but it would mean that the side shots could not be cancelled when hitting PF (or it would become impossible to shoot through an empty bridge area - the doubled side shot would always hit PF).

 

Possible workaround using the ball sprite instead, but its dark green color does not show up all that well onscreen (plus, it would become necessary to reposition the ball before displaying the fuel gauge).

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What a nice hack packed with value. It's much easier to fly full speed and blow everything up. While that may sound likes it's now too easy, it isn't. Remember the fuel tanks are more easily destroyed too. And then you need to slow down, change strategy momentarily to successfully refuel.

 

With all these hacks and stuff It's like getting new game options on our 40-year old games. Or think of it as firmware updates and upgrades.. heh!

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Got most of it ironed out...may get a stray duplicate missile just below a road, tho.

Here's that test (attract & BW code removed). This name already taken?

 

Very cool hack. Totally renews the game.

 

Can the color cycling playfield be added as an option as well? Is that something you're already working on, or is there not enough CPU cycles?

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Cycles are a non-issue for the playfield...it can be set to a new color offscreen...but what is it based on here?

 

Wouldn't a bridge counter be better?

 

For practical purposes, probably. But I'm referring to the constant color cycling (every couple seconds) of the Fantasy mode shown in the video. No reason for it, except awesome flare -- perhaps toggled via the Color/BW switch or a difficulty switch for those who are sensitive to the color changes or just don't like it.

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