What Is a Prime?

A prime is a wall of consecutive blocked points. Each point in the prime has 2 or more of your checkers, making it impossible for opponent checkers to land there (or pass through).

Prime Length Rolls Blocked
2-point 1 roll (matching the gap)
3-point 3 out of 6 values
4-point 4 out of 6 values
5-point 5 out of 6 values (only a 6 can escape)
6-point All 6 values — completely impassable

A 6-point prime is the ultimate positional weapon. An opponent’s checker trapped behind a 6-point prime has zero legal moves and must wait for the prime to break.

Building a Prime

Start with Key Points

The most natural prime builds from the bar point (7) through your home board:

  • Points 7, 6, 5, 4, 3, 2 = perfect prime
  • Start by making the highest points (5, 6, 7) and extend downward

Use Builders

A builder is a loose checker positioned where it can help make a point:

  • Checkers on the 8, 9, 10, 11 points are excellent builders
  • When you roll the right number, the builder slides into position to complete a point

Slot and Cover

Slotting means deliberately placing a blot on a point you want to make:

  • Risk: the opponent might hit it
  • Reward: on your next roll, you cover it and make the point
  • Slotting is a key prime-building technique in the early game

Advancing the Prime

A prime in the outer board (7-12) eventually needs to move into your home board. The technique:

  1. Peel from the back — take a checker from the rearmost point of the prime
  2. Extend the front — use that checker to make the next point forward
  3. Maintain the length — the prime stays the same length but shifts one point closer to home

Challenge: You need the right dice rolls to advance smoothly. Bad rolls can force you to break the prime prematurely.

Keeping the Opponent Trapped

The prime is only valuable if the opponent has checkers behind it:

  • Before building the prime, trap opponent checkers behind it through hitting or blocking
  • The more enemy checkers behind your prime, the more devastating it is
  • Even one trapped checker gives you a significant advantage

Timing

The prime must last long enough to be useful. Timing means having enough flexibility to maintain the prime until you’ve brought your remaining checkers home:

  • Checkers in the outer board provide tempo
  • Extra checkers on the back of the prime help with advancing
  • Too many checkers already home = timing crunch

Priming vs. Blitzing

Feature Priming Blitzing
Approach Positional — build a wall Tactical — hit and build
Risk level Moderate High
Best when Opponent has checkers you can trap Opponent has blots in your home board
Downside Slow; requires good timing Can backfire; opponent may anchor
Typical result Win by position Win by gammon

Many games involve elements of both. You might blitz to trap checkers, then build a prime to keep them locked up.

Common Prime Mistakes

  1. Building a prime with no one behind it — a prime without trapped checkers is just a pile of checkers
  2. Neglecting timing — your prime breaks before you bear off
  3. Making the wrong points — a prime on points 2-7 is much better than 1-6 in the middle of the game
  4. Ignoring your back checkers — while building a prime, your own back checkers still need an escape plan