It's the book of buns. The rules of rabbits. The laws of lagomorphs.

A lot of these are things you're supposed to figure out yourself. But I didn't figure some of them out, so I'm listing them all out for you. Please let me know if I missed something.

Accurate as of version 1.09.

Buns have these drives, in descending priority:

• Don't go into dead ends
  
• Get treats
  
• Don't stay where they can see you
  
• Don't stand still where there's a wall, hole, or trap on both the left and the right. Edit: User Mokesmoe says holes don't count for this. They still count for dead ends, as described below.

A square is a dead end when a bun can clearly see that there's no way to move left, right, or forward from it without running into walls, holes, traps, or miscellaneous obstacles. For more information, see What Buns See.

• If the only visible way to move left, right, or forward from a certain square is to move into a dead end, that square is also a dead end.
  
• If a bun can't see an obstacle on at least one side, it will always assume there is no obstacle and no dead end.
  
• You don't make a dead end if you block the path yourself, but there's never a good way to use this.

Buns can make multiple moves every time you move once. They'll fulfill every drive until all are either fulfilled or impossible, ignoring lower-priority drives whenever higher drives are both possible and active.

• Buns can activate a higher drive while they haven't finished fulfilling a lower one.
  
• “Don't go into dead ends” is prescriptive. If the bun sees that it's ALREADY in a dead end, both “don't go into dead ends” and “don't stand still when side movement is obstructed” will deactivate.
  
• However, “don't stay where they can see you” will remain active if the bun is in a dead end.
  
• Untested: does “get treats” remain active when a bun is in a dead end?

Directional priority: buns move straight if they can, left if they can't, right if they can't move straight or left. Buns cannot move backwards.

• When “get treats” activates, forward is the direction of the treat.
  
• When “don't get close to you” activates, forward is the opposite direction from you.
  
• When there are obtainable treats on both the left and right, but not forward, left becomes the new forward.

When a bun changes drives, whatever it does next is a separate action. “Forward” can CHANGE according to the new action.

• Say a bun is north of you, and it moves up to you to get a treat. “Forward” was south. Now that it wants to get away, “forward” is north.

For most things, buns see an infinite distance in each cardinal direction (north, south, east, west) until blocked by walls or the edge of the screen.

• When looking for traps, holes or pseudo-walls (e.g. pillars), buns can also see one square diagonally. They can't see diagonally when looking for walls, treats or you.
  
• The edges of true walls (i.e. not pillars) stand on the border between two squares, and are “part of” both squares. This is how buns see a wall that's to the side of their path.
  
• But see Tiny Tunnels for a case where buns can't see walls.
  
• Traps, holes, and pseudo-walls are ONLY attached to the square they're on. If they're not in a cardinal direction, buns won't spot them until they appear in diagonal vision.

You're less visible than a wall. Buns can't see you if there are three or more empty squares between them and you.

• They also ignore you if there's a wall between you and them, even if you should be visible through a tiny tunnel.
  
• Buns can still notice you if there's a trap or a hole between you and them.

Buns that move on top of each other will stack.

• If ANY two members of the stack have never stacked with each other before, you'll immediately get a baby bun for each new pair. (Apparently, buns are hermaphrodites.)
  
• You'll still keep the baby if you don't or can't pick up the stack afterwards.
  
• There are important unlocks specifically for catching baby buns.
  
• More on this under Tiny Tunnels and Home Capture.

If a bun's drives make it unable to stop moving, it will eventually fall asleep. Normally, this only happens when the bun repeatedly moves through tiny tunnels.

Two buns can move at the same time. This mostly matters when they move through tiny tunnels.

Buns have no priority for or against moving into tiny tunnels, though the normal priority against dead ends applies.

Stacked buns cannot enter tiny tunnels.

Buns can see through straight tunnels to see treats, traps, and holes.

Buns cannot see diagonally into, through, or out of tiny tunnels.

• A bun looking through a tiny tunnel cannot sometimes doesn't see wall edges that are “part of” the sides of squares on the other side.
  
• Edit: I think by default it sees the walls, but it stops seeing them if it's lured by a carrot? But it still stays away from carrots that are in a dead end that isn't on the other side of a tunnel, so I'm not sure why tunnels change that.
  
• If a bun can see a one-square L-shaped tunnel, and it can see a trap in its diagonal vision, it can figure out that the turn leads into the trap. Complex reasoning, by bun standards.
  
• For some reason, buns can’t make the same deduction if a one-square L-shaped tunnel leads into a hole. They’ll fall in. (But see Traps and Holes.)
  
• As soon as a bun enters a tunnel, it will forget about all traps and holes it could see while outside the tunnel.

Buns cannot stop moving until they either leave the tiny tunnel or have walls on three sides.

• If they hit an intersection in the tiny tunnels, and they see a treat or a dead end, they can change their drive and turn left or right.
  
• However, a bun in tiny tunnels cannot turn around even if its drive changes.

If two buns move into the same square of a tiny tunnel, that square will explode, freeing and stacking them.

• This can happen when they both move somewhere in the tunnels that has walls on three sides.
  
• This can also happen if both buns enter separate tunnels, but directional priority brings them together.
  
• Untested: presumably this would happen if two buns changed screens into the same square and it was a tiny tunnel. See also Changing Screens.
  
• Update: there's now a mechanic called "bunny bump" that happens when it's unclear which square should explode. I haven't tested this mechanic and don't know how it works.

Buns have no priority for or against moving off the edge of the screen. This can move them into new areas.

• You can follow them to the new area and catch or stack them there. But see Home Capture.
  
• From the new screen, you can then chase the bun into a third screen, or back into its original screen.

If you change screens, and you don't change to the same screen the bun moved to, the bun will return to its original screen.

When you change screens, the bun can move before you actually enter the screen, preventing you from catching it. However, you can catch the bun if it has nowhere to move.

When you change screens, you can move into a space that has a wall. The wall will be destroyed, even if it's strong.

When a bun changes screens, it can move into a space that has a wall. The wall will usually be destroyed.

• If a bun moves into a tiny tunnel by moving areas, and the tiny tunnel faces the same way the bun is moving, the tunnel will not be destroyed.
  
• You don't have to move into the same square the bun moved into.
  
• If two buns that aren’t stacked move offscreen to the same square, you move offscreen to that square, and directional priority pushes them into a tunnel adjacent to that square, they’ll stack inside the tunnel entrance and destroy it.
  
• Untested: if two buns move offscreen into a square that contains a tiny tunnel, you move into the same square, and there’s one more square of the tunnel, will you destroy the first square and the buns stack in and destroy the second square?

When you change screens, then come back, all your tool uses will always be restored, and all damaged walls and floors except the wall you walk into will always be repaired, regardless of where you enter from.

• Sadly, you don't get your tool uses back if Paquerette says she can't go there yet.

A bun that moves into a trap will be immobilized.

A bun that moves into a hole will change to the lower screen. See Changing Screens.

For how buns avoid traps and holes, see What Buns See.

When a bun can't escape, it generally follows its directional priorities.

• Edit: there used to be weird behavior when choosing between dead ends, traps, and holes, e.g. sometimes going right into a dead end rather than left into a hole. This is supposed to be fixed in 1.09.
  Edit to the edit: still some weirdness. You can see this on C-23--the bunny would rather go right into a one-square L-shaped tunnel and then into a trap than go straight down a hole, even though bunnies usually avoid one-square L-shaped tunnels that go into traps.

You can walk over traps.

You can pick up traps and reuse them.

Traps can’t be placed on flame floors.

It's rare but possible for there to be a hole hidden under a wall.

• You can only find it when the wall is destroyed.
  
• Yes, this is irritating.

Each use of the pickaxe destroys one weak wall or weak pseudo-wall (e.g. pillars.)

Drives permitting, a bun that sees a treat will run towards it and eat it

Buns will ignore treats that are on the other side of traps, holes, and you. Nice try.

The bun will stop if it gets close enough to see a trap or hole in its diagonal vision that creates a dead end.

Credit to Shade for this one: treats can nullify the "don't stand still with walls on both sides" rule. If there are walls on both sides of the treat, but it's not in a dead end, the bun will move to the treat and then stay there until you get close to it.

Treats are still "active" on the turn they're eaten. If one bun eats the treat before another can get it, the other will still run to the same place and stack.

Buns never stop wanting more treats. Their hunger is all-consuming.

If a treat is uneaten, you can pick it up and place it elsewhere.

Treats can’t be placed on flame floors.

Everything else is under What Buns Want and What Buns See.

Each use of the shovel creates a hole under you.

• You can only go down the hole if you move off it and back onto it.
  
• Thus, shovels are useless if you're completely walled in.

The shovel cannot be used on strong floors.

• Flame floors are always strong.
  
• If a wall is destroyed, it will never have a strong floor or a flame floor under it.

If you move into one of the holes without moving to any other screen, all walls directly below ALL holes you dug will be destroyed, including strong walls.

If you move down a hole, but don't move to any other screen from there, you can move back up any of the holes you dug.

• This can (re)destroy a wall above you.
  
• All the holes you dug will vanish, though.

If you catch a bun on the screen it started on, it will usually be a home capture.

• If you chase the bun to another screen, then chase it back to its original screen, it's still a home capture.
  
• If buns are stacked, you may home capture one while regular capturing another.

If stacked buns ever have priorities that say to move into a tiny tunnel, but they can't because they don't fit, catching the buns afterwards will not be a home capture.

• Hat tip to Aub for this one: if buns would normally stop moving because they would be capable of moving to the left or right into a tiny tunnel, but they're stacked, they keep moving forward. Catching them afterwards is not a home capture.
  
• You can tell the home capture is no longer possible if the stack wobbles.