No.

Although Halo was originally intended to be the engine for a new version of Myth, that idea was abandoned early in development.

Although Halo was originally intended to be a third-person game, like Oni, and there was some technology sharing between the two development teams, Halo does not use Oni's engine.

The upcoming game Myth 3, being developed by Mumbo Jumbo for Take Two Interactive, uses a Myth 2 engine modified to create a fully 3d game. That engine is in no way related to Halo or Oni.

Bungie released editors with its previous games in the Myth and Marathon series.

It has been rumored that the underpinnings of the Halo engine are highly customizable; however, the Xbox itself will not have any capacity to run such an editor, and it is not believed that there will be any mechanism for altering the game on that platform.

It is not yet known how editable the release of Halo for the Windows and Macintosh will be, or whether it will ship with an editor and if so for what platform.

Marty O'Donnell and Mike Salvatori, formerly known as Total Audio in Chicago, did the sounds and music for Halo.

Marty O'Donnell accompanied Bungie to Washington state; Mike Salvatori retained the Total Audio name and remained in Chicago.

Halo's musical score is supposed to be dynamic, reacting to events within the context of the game world.

Because of the nature of Halo as an Xbox title (at least at first) beta testing has been held on the Microsoft campus in Washington state. There have in the past been solicitations for fans in the area to participate in such tests.

It is not now known whether or not there will be a public beta test for the Windows and Macintosh version of Halo, and if so when or what the requirements for participation would be.

Halo has been in development since around the end of Myth's development, during the winter of 1997. It proceeded through the development of Myth II, briefly interrupted by the final development phase of that game.

At the time of this update in October of 2001, Halo has been in development of some sort or another for nearly four years.

When development began, Halo was slated for a simultaneous release for the Windows and Macintosh platforms sometime in 2000.

There are currently no indications that Halo features deformable terrain. This was never more than a rumor.

Not strictly speaking, at least not in the sense that objects are persistent in massively multiplayer online games like Ultima Online or their ilk, although it was speculated that Halo might utilize such an architecture early in its development.

Bungie has stated that within the solo campaign, objects are persistent in the sense that if the player sacks and destroys a Covenant base, it will stay that way unless there's action taken to change that.

A particle effect weather system certainly exists, and such environmental effects as snow have been displayed. And where there is snow, there will likely be rain, and probably other assorted effects.

Early on it was speculated that Halo might operate like a simulation, with real-time cycles of day and night based on the geometry of the Halo system and a realistic physics system.

While the physics of Halo's engine are certainly quite advanced, there's been little reason to believe that at this point it takes into account such celestial events.

Possibly yes. One account describes the ambient life as being very big, perhaps large enough to ride on, and possibly intelligent.

The demonstration movie from E3 in 1999 featured two kinds of ambient life-- a large, dinosaur-like creature, and a herd of small, toothy animals.

However, neither has been seen in any builds of Halo since that time, and it is not known if they will be present in the Xbox release version of Halo or subsequent versions.

Soell is the unofficial name of the Halo system primary star, named for Bungie's Matt Soell. There is the possibility that there is more than one star in the Halo system, as suggested in the second Cortana letter quote the suns are shining, but little other information is available.

Basis is the official name for the moon of Threshold which the Halo orbits with. Little else is know about it, except that it has been called Zartmoon and Seropia in the past.

Threshold is the name of the large, orange colored planet seen in the demo hologram room sequence. According to a Bungie preview quote, it is a large gas giant planet, and the ringworld orbits it on a halo (or lagrange) orbit between it and a smaller moon planet.

One of the possible connections between Halo and Marathon is the idea that the Halo is of Jjaro (or Jjarro) origin. This race had the ability to move entire moons through space.

The Halo is a ringworld that may be crucial to tipping the scales in the war between the humans and Covenant.

It is believed to be an ancient artifact of a long departed race (perhaps the Jjarro of the Marathon series).

The Covenant is a alliance of three alien races, believed to be fanatically religious, and engaged in a war with mankind. They are very advanced, but for some reason see the player as their Devil-it has been hypothesized that this is because the player is a cyborg, which may be taboo in their culture.

In addition to the humans and the Covenant races, there is apparently a third race that appears in Halo. They are possibly the constructors of the Halo and/or residents of it.

Cortana is a shipboard AI (articificial intelligence) from the human craft Pillar of Autumn. Apparently the Covenant are after her, and it's your job to stop them from getting their hands on her.

Early in Halo's development and long before its announcement, several emails were sent from computers at Bungie under the name Cortana that elicit connections the Marathon universe and possibly AIs from that story, perhaps Durandal.