Version 1.1 was a critical technical update for the WAD file. The original v1.0 release suffered from a major bug where the music was improperly mapped, causing tracks to play on the wrong levels or not at all.
I notice you've mentioned — that appears to be a custom WAD file for Hexen (specifically Hexen: Deathkings of the Dark Citadel, or a mod based on it), likely from the Doom/Hexen engine modding scene. hexdd.wad v1.1
v1.1 addressed stability issues when running the expansion on the updated Hexen engine (v1.1). Without this synchronization, players often faced "Z_Malloc" errors or hard crashes during level transitions. Version 1
Deathkings of the Dark Citadel consisted of 20 new single-player levels spread across three massive hubs: Hub 3: Citadel: : You can verify your
Features tight, claustrophobic corridors and heavy trap-based gameplay. Hub 3: Citadel:
: You can verify your version by checking the file size of your HEXDD.WAD . v1.0 : ~4,429,700 bytes . v1.1 : 4,440,584 bytes . How to Upgrade