Worm Visitor/Frog Adventure - Unused 2-in-1 menu

[TVS64]

Good morning, fellas. So, while I was looking through the code of Frog Adventure yesterday evening (particularly NewRisingRun's standalone dump), I found that a short string of code (hex values 7F80-7F8E in PRG ROM) was used to determine whether Worm Visitor or Frog Adventure start up after the "Sachen" splash screen concludes. When I modified a few of the values, I noticed that only hex addresses 7F81 and 7F89 did not immediately crash the game. Modifying the values in hex address 7F89 didn't have any interesting results (it simply chose between both games), but I eventually discovered that setting hex address 7F81 to either 00 or 16 chose neither game, and instead booted to an unused 2-in-1 menu, with all its code and graphics left intact (as seen in the image below).
Of course, this can also be done by setting memory address FF81 to 00 or 16, or by using the Game Genie code "AAEYOY".

[SF-Human]

Thanks for the information!


Attached a pre-modified ROM below.

[TVS64]

You're welcome, and alrighty then.
(setting said value to 16 does cause it to accept inputs as soon as that menu loads, though, so skipping the "Sachen" splash screen could lead to accidental selection of Worm Visitor)

[NewRisingSun]

Most interesting, thank you. I have re-added the copyright year to Frog Adventure as well, attached.

[SF-Human]

Also, I compared the ROM of both games and only a few bytes were different. Makes me wonder if the "game" can be switched via a soldier pad like DKC4 or other means on a theoretical standalone release (which did not happen), or both games were meant to be on an unreleased 2-in-1 multicart like their 2-in-1 light gun games.

[NewRisingSun]

I am not sure what you compared, but the first 32 KiB bank is very different from the second one. I think it was supposed to be a 2-in-1 multicart that we just restored with menu and all. Both games were just extracted from Sachen Super Cartridge Ver. 8. They are essentially one game with two "modes".