Routes

Not sure which category to start with? All Levels (Inbounds) and All Levels (OoB) are the most popular, but you can start with any category.

Categories (with average run time estimate):

All Levels (OoB): 20-30 minutes, lots of out of bounds skips (which range from easy to expert)
All Levels (Inbounds): 20-30 minutes, mostly movement optimization, fewer all-or-nothing tricks than OoB
All Puppies: 45-55 minutes, collect 6 puppies per level, a mix of OoB and inbounds strats
100%: 1.5-2 hours, collect 6 puppies, 100 bones, and 6 stickers per level, almost entirely inbounds
Any%: 3-6 minutes, uses Start Menu Warp to skip straight to level 17 (Hedge Maze), several hard OoB tricks

All categories (but All Puppies) have written guides.

All Levels and All Puppies have video guides.