Seven

Bungie has been using the number 7 recurrently in its games as well as in the surrounding "Bungie mythos" (e.g., there is a 7-point plan for world domination).

The theme also employs powers of 7 (49, 343, 2401...) as well as the derived "Bungie numbers", 4, 3 and 10.

Here are a few occurrences of 7 in Oni

• Most of the OST is by Power of Seven.
• The digits of the year 2032 add up to 7.
• Konoko's Chrysalis was implanted at age 7.
• Konoko can wear 7 different outfits in Oni.
• Konoko wears a stenciled 07 in the intro.
• Broken mirror means 7 years of bad luck.
• There are 7 rooms in the training course.
• 7 images in Hasegawa's diary (Chapter 11)
• It takes 14 days to grow an SLD.
• There are 14 = 2x7 chapters (w/o training).
• There are 6 hypos/clips/cells + the 1 in use.

The last two are, of course, disputable ^_^
Other disputable ones can be disputed HERE

As far as community efforts go, among other mods, the Anniversary Edition project uses "it's a seven" as a tagline.