A mod for Halo 3: ODST that drastically improves the AI in the game, both friendly and enemy. It also changes and rebalances the sandbox and other elements. All among other things. Covers the entire Halo 3: ODST campaign and Firefight experiences.
Main download with all the playable maps. Only download necessary to play the mod. Yes, you still need to use map replacement with the mod. :(
(Optional) Cutscene maps for the mod. Not necessary to download, but included for completeness.
Standalone mod readme that goes into more detail about the changes. (Because it didn't fit in the description.)