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Changing the first room of the game

Started by SabbaticGoat, October 11, 2017, 05:58:13 PM

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SabbaticGoat

Salutations and such,

What determines the starting room of a new game? I'd like to point the game to start at a room other than the Ceres Elevator room.

Along similar lines, how does the game transition from Mode 7 rooms to normal rooms? In other words, why does the game start with the intro sequence, send you to the Ceres Elevator room, and then send you to room $7DF8D? Is editing this starting sequence even possible?

Thanks.

SabbaticGoat

P.S. I just discovered the "Hide Intro" action in SMILE JX that forces that game to start after Samus lands the ship in Crateria. How does the "Hide Intro" action accomplish this?

PHOSPHOTiDYL

There's the hide intro feature in smile, however only one save file will properly work.
There's the skipintrosaveswork, it involves some asm knowledge, you can set your start point.
There's skip ceres, easiest patch to use, pretty sure all the save files still work.

Ceres is a nightmare of code, gamestates are very delicate, it's best to avoid messing with.
Gamestates are bank $82 though. Small piece of code for you...

;//[001F = setting up new game]
$828041 A9 06 00    LDA #$0006
$828044 8D 9F 07    STA $079F  [$7E:079F]
$828047 9C 8B 07    STZ $078B  [$7E:078B]
$82804A 22 93 9E 80 JSL $809E93[$80:9E93]       ;//clear timer RAM



First it loads #$0006 (aka ceres) & stores it to the region number.
Stores zero to what save station in region to load from (aka ceres elevator).
Then jumps to a routine to clear the timer.

This would be the obvious place to edit, however ceres is a nightmare & it just don't work like that.
Changing to crateria here will still start you off as if you were on an elevator.

The hide intro just changes one byte to skip a branch of code if I remember right.
Skipintrosaveswork was designed if one wanted a difficulties patch & the ability to skip ceres.
It's from the same routine as the hide intro, if you want to do a bit of studying & compare them.

Skip ceres has two patches, one with the fly to zebes cutscene, one without.
I'm pretty sure there's also been other hex edits for starting at the landing site.
Also, I'm sure there's another patch that lets you set your starting point.

Bank $82 has the goodies you're interested in.