Native 16:9 support without stretching the UI, which was a major technical addition in this patch.
To understand why "1.31" is the specific target, look at the evolution: repack warcraft 3 frozen throne 131
Before 1.31, all custom maps went into a single Maps/Download folder. Searching for a specific map took forever. Patch 1.31 introduced —you can organize your library into Maps/Download/TD , Maps/Download/AoS , etc. The repack preserves this. Native 16:9 support without stretching the UI, which
The Last Repack