Halo 2 supports custom maps (and automatic downloading of those maps!)
- Custom Map Folder: %userprofile%/Documents/My Games/Halo 2/Maps
- Place all custom maps here (there is a 50 active map limit)
- Alternatively you can download the Custom Map Adder: http://www.h2pc.org/downloads/files/Custom Map Adder.exe
- Map Repo: https://www.h2maps.net/Cartographer/CustomMaps/
- In game map downloading occurs in the pregame lobby. Cartographer attempts to match the current custom map with a map file in the repo, and downloads the map
- 50 map limit is still an issue, keep that in mind.