In *EtherealBoy*, the player is given a GameBoy ROM `game.gb`.
Many older games consoles use the concept of a *tileset*, a set of *n*x*n*pixels *tiles*, which larger images for the background and sprites areconstructed from. Famously, the hedges and clouds in *Super Mario Bros.* onthe NES use the same tiles.
![Donkey Kong palette](https://tilde.town/~kirby/ctf/swampctf2018/assets/dk-palette.png)
Many games require a font to construct text from, and thus dedicate some tilesto a full alphabet and numbers. These are logically laid out in an order you'dexpect, A-Z, 0-9. When we inspect the tileset of the provided ROM (this can bedone using an emulator such as bgb), however, we instead see the characters laidout to reveal the flag `flag{und3r_th3_hood}`.
![game.gb palette](https://tilde.town/~kirby/ctf/swampctf2018/assets/gb-tiles.png)