Blue - Touch all sections in game, not including secret sections.
Orange - Complete all secret sections, including Blank, Minute, and Anticipation.
Pink - Max out the skill tree. You'll need to be at least level 80.
Teal - Collect every box effect (NOT mutator!!!! People make that mistake too much!).
Red - Beat THE Tower of Hell.
Purple - Do all of the above, except for Red.
There is also
Green - Buy the Infinite Yxles Gamepass (no longer obtainable)
Silver - (Builder Exclusive)
Gold - (Admin Exclusive)
Rainbow - (Owner Exclusive)
Blue is the most common halo to get by the way
There are starting to be too many different halos
What do you think?