The Voya Nui Online Game was delayed for playtesting to avoid the kind of glitches present in Mata Nui Online Game II: The Final Chronicle.1
The Voya Nui Online Game was still in playtesting in mid-February.2
The Voya Nui Online Game was still being playtested at the end of August.3, 4
All of the Rahi in the Voya Nui Online Game were canon.5, 6, 7
The Rahi of the Voya Nui Online Game were official. This included Gafna and Burnak.8
Greg Farshtey stated that the blocking lava ape [sic "Blocking Stone Guardian, or Ape, or something like that"] was not canon to his knowledge.9
The Rahi seen in the game weren't built as LEGO models prior to their inclusion.10
Gafna, Burnak, lava apes, and mobile Nektann seen in the game were all canon.11
The different types of Nektann seen in the Voya Nui Online Game were canon.12
Greg clarified that he can't say the Voya Nui Online Game was mostly canon with the exception of some story elements because he hadn't played it and wasn't involved in its design. The only thing he confirmed were the Rahi, which were canon.13
The Voya Nui Online Game was not intended to match the 2006 storyline because it was supposed to be released so long before the end of the year that, had it been the actual story, it would've revealed the ending of the year early.14
Greg Farshtey stated that the Toa-like figure found in the files for the Voya Nui Online Game was not canon to his knowledge and was something done for the game as a kind of extra.15