A ROM is a .nds file (roughly 128MB). A patch is a tiny file (under 10MB). You never "download" the full Sacred Gold game from the creator. You download the patch from Drayano’s GBAtemp thread or Google Drive, then apply it to a clean HeartGold ROM.
: Many Legendary Pokémon and rare starters are added as scripted overworld encounters or gifted by NPCs, making the world feel more populated and rewarding. Revised Move Sets and Abilities sacred gold pre patched rom upd
: Without specific context, it's hard to define what "Sacred Gold" refers to. It could be a title of a game or a specific hack/version of a game. A ROM is a