Posted by Natalie

Hatkirby
Hatkirby posted on www.fourisland.com

How Frog Game Allows You To Modify Map Data

Two adjacent overworld screens. There are two trees in the center.

It might look like two trees, but it's actually one. The borders of a top-down map are the same logical space as the borders in the adjacent maps, so those two trees actually represent the same object. It would be a finnicky edge case for the game to have to write two terrain edits to memory specifically when this tree gets destroyed. Instead, both trees are assigned the same global coordinates:

  • Left tree is on map (14, 2) at tile (9, 3). Global coordinates are (14 * 9 + 9, 2 * 7 + 3) = (135, 17).
  • Right tree is on map (15, 2) at tile (0, 3). Global coordinates are (15 * 9 + 0, 2 * 7 + 3) = (135, 17).

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  • #kaeru
  • #video games

Hatkirby has been writing a very intriguing series of posts on reverse-engineering For Frog the Bell Tolls, a lovely and underappreciated gem of the Game Boy's library. This is actually just the most recent post; you can read the whole series here (start at the bottom and work your way up). This has a lot in common with my own currently-on-hold reverse engineering projects, and it's interesting to see a lot of the same problems tackled for a very different piece of software with very different tools for working with it.

Hatkirby has been writing a very intriguing series of posts on reverse-engineering For Frog the Bell Tolls, a lovely and underappreciated gem of the Game Boy's library. This is actually just the most recent post; you can read the whole series here (start at the bottom and work your way up). This has a lot in common with my own currently-on-hold reverse engineering projects, and it's interesting to see a lot of the same problems tackled for a very different piece of software with very different tools for working with it.

  1. for frog the bell tolls

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