[TheAceOfHearts]

In the Pokemon Blue codebase they use 2 flag variables to distinguish between the different games, these are `pokemon_type` and `pokemon_type_blue`. The name of the second flag definitely hints that it was added later in development.

These are the values for each game:

    Green:  pokemon_type=0 pokemon_type_blue=0
    Red:    pokemon_type=1 pokemon_type_blue=0
    Blue:   pokemon_type=1 pokemon_type_blue=1

The general pattern for branching between game variations looks like this across the codebase:

    ifn pokemon_type
      ifn pokemon_type_blue
        ; blue
      else
        ; red
      endif
    else
      ; green
    endif

Conditional assembly directives like `ifn` are resolved statically during assembly, so only the code between matching conditions is included as part of the output. To anyone interested in exploring this a bit more, I'd recommend reading Chapter 8 Section 13 of the DOS version of The Art of Assembly Language Programming [0], which starts on page 43 of the linked PDF.

Bonus fun-fact: In the Pokemon Yellow codebase it says `pokemon_type=1` is yellow, while `pokemon_type=0` is pink! This suggests to me that the idea of Pokemon Pink with Jigglypuff as your starter was probably being floated around but it was eventually scrapped. (The only remaining options for a pink starter pokemon with a pink evolution in the original 151 would be Clefairy and Slowpoke, neither of which are very cute.) The idea of Jigglypuff as a starter is further supported by her appearance alongside Pikachu on the roster of the original Super Smash Bros. which seems rather unexpected unless they had bigger plans for her.

[0] http://www.plantation-productions.com/Webster/www.artofasm.c...

[abaga129]

I found some supporting evidence from bulbapedia "Clefairy was originally going to be the official mascot of Pokémon, but Pikachu was used instead due to the popularity of the anime and Pikachu's familiarity with fans".

Source: https://m.bulbapedia.bulbagarden.net/wiki/Clefairy_(Pok%C3%A...

Very cool find about the pink version!

[abaga129]

I seem to recall watching a video somewhere, perhaps on Didyouknowgaming, that Clefairy was intended to be the Pokémon mascot before Pikachu. I could be completely wrong here, but if so that is really cool to think it may have had its own game!

[advance512]

Very cool, uncovering game development history via the source code.

Thanks for this!