[cliff]

Other games have 'start with partial download' technology. In fact, the core tech of the team that eventually created Valve's Steam was downloading assets on-the-fly so that you could start playing a game before everything was downloaded.

I worked on Guild Wars 2, which has this feature. I made a first prototype of it that streamed all content on-the-fly. It's pretty easy to implement - you have an abstraction that asynchronously loads a file off of the disk, and you can just make that download from the network instead.

The tricky part is when you want to ensure all the assets are there for a specific area before you load in, or simply knowing what order to download things in. For example, there was a starter area of Guild Wars 2 that spawned monsters from many other areas, this meant that the manifest of what was needed was enormous for that area.

So the 'playability' threshold becomes a trade-off between game experience (assets popping in as you play) and quick entry.

[SketchySeaBeast]

Guild Wars 2 needs more respect from the MMO community. The ability to do testing on the live servers, or enable patches with a client reboot and no server downtime, is great.