Freedoom 0.9, what's in a number?
There seems to be much confusion that the current version number, 0.9, represents the project as being 90% complete. This is not correct.
Freedoom uses a traditional version numbering scheme, adopted by many free software projects, where 1.0 represents a complete project in which no more groundwork must be performed. It should be noted that development does not stop there. In the earliest days of the project, this was solely to create a Doom II-compatible IWAD, a single game, which is now called Freedoom: Phase 2. Since building such a game is a long process, we could not possibly have all the necessary resources to make a fully-compatible replacement for Doom II, and was initially released as version 0.1. Before the release of 1.0, versions 0.x are used to represent work based on milestones.
A progress indicator for Freedoom is difficult if not impossible, because while it might be easy to count the number of resources still missing from Freedoom in comparison to Doom, such a number would not represent resources of poor quality, and we should strive to have all of it of the highest quality possible. In addition, our goals have altered over the years. FreeDM had started out a fork that became abandoned early in its life, before being merged back into the primary Freedoom project and presented as part of the 0.5 release. If the versions were percentages, Freedoom may have had to go backwards, which would make no sense. Similar discrepancies would have happened when we dropped the "shareware" target, added Freedoom: Phase 1, or dropped the resource PWADs. Such actions cause the project's goals to change, adding or removing work from the project, and we cannot represent it with an ever-increasing progress indicator.
As part of this, the version number is not a decimal number, it is merely two numbers separated by a dot. 0.9 was not numbered because it is "0.1 larger" than the previous, but rather because 9 was one larger than 8, when concerned only with the second component. The first component is still 0 because Freedoom 0.9 is not yet complete: Phase 1 still lacks many levels, there are still sprite overhauls in-progress, low-quality or missing resources, and an assorted arrangement of known bugs (we tried to keep the major bugs out of 0.9!). It's also worth noting that the project has released a few minor/patch releases in the past, notably Freedoom 0.6.1 through 0.6.4, which were not considered major enough to become 0.7 yet, and introduced a third component to the version number.
What version number will the next major release be? In short, we do not know. It could be Freedoom 0.10, it could be Freedoom 1.0, it depends on the work put into the game post-0.9 and cannot be properly foreseen. We just hope that Freedoom 0.9 represents a better quality release than all of the previous ones, and we can only hope that future releases will be even better! :)
Hope this post clears up some confusion about what 0.9 as a version number means, and what's in store in the future.