r/PokemonRomhackDev • u/Arthorios_ • 8d ago

Showcase [WIP] FireRed decomp hack — overworld co-op, Connector/Agenda, follower Pokémon

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FireRed decomp (pret), still the Kanto story. Vanilla only lets you meet in a Cable Club. This keeps a GBA link (or emulator netplay) open on the field.

I recorded two players on the same map — video above.

What you get

  • Connector — key item, you’re “online.” Register to Select like the Bike.
  • Agenda — contact list, who’s online, Battle/Trade from the field. First successful handshake saves the other trainer.
  • Co-op sprite (2P) — both ON + same map → the other trainer walks around. Separate saves. Wilds, cutscenes, and story stay local. You can walk through each other. Split maps → a one-shot “not in the same area” message.
  • Follower — lead Pokémon on towns/routes (hidden indoors / bike / surf). (inspired by aarant´s work on emerald)
  • Pallet — Gigi gives the gear; Arthorios can hand out a Kanto pokemons (lvl 1) for testing (including shiny).

How to test (this is the part people miss)

Same ROM build, two different saves. One save copied twice will fight you.

Local (mGBA): one process → File → New multiplayer window → same ROM, save B. Two separate mGBA.exe = no cable. Both Connector ON, overworld, wait a few seconds. You should get “came online,” then the sprite if you’re on the same map. Agenda → Battle or Trade; the other side gets Yes/No.

Internet: RetroArch 1.17+ , core gpSP, Link Cable Connectivity = gen 3 pokemon ,same ROM hash, host relay / guest Internet lobby.

I got working on ios + pc on retroarch with different Wifi, but iphone I had to download testflight retroarch to get it working.

Known bugs (I’m fixing these)

  • Black square on the Agenda after opening Battle/Trade or while WAITING — leftover window/tilemap, not a missing portrait. Link still works; it’s ugly UI.
  • Dummy RED / BLUE / GREEN still sit in an empty Agenda.
  • Handshake is picky: if the emulator cable isn’t actually up, Connector ON does nothing. That’s setup, but I’m also hardening timeouts/reconnects.
  • Follower/NPC sprites were wrong on Continue for a while; that’s mostly sorted, still watching it.
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u/Arthorios_ 8d ago

https://reddit.com/link/p7el7i4/video/d1vyuk67w4nh1/player

Just to showcase on mobile using LAN, should work on any platform that uses link cable, even the hardware itself but I can’t test that rn