This was one of the most stable final builds. If you find a legitimate mirror of this version, it often retains all its charm even without the "Gold" registration status. The Modern Alternatives
Because it was , the game would frequently prompt users for a registration code to remove "nags," unlock all tile sets, and access higher resolutions. The Reality of Registration Codes Today
If you have the nostalgia bug and want to run the game on a modern machine, you don’t necessarily need to hunt for a sketchy registration code.
Online play that was revolutionary for its time.
Kyodai Mahjongg 2006 is now widely considered abandonware . While not technically "public domain," it is no longer commercially supported or enforced.
Reputable digital preservation sites like The Internet Archive often host the installer files. In many cases, community members have uploaded versions where the registration prompt is either bypassed or a "legacy" key is provided in the comments for preservation purposes.