Authoring chess courses for Chessreps

The four authoring rules

1. One chapter, one tree Chessreps has no concept of chapters. The whole course is a single PGN tree with a single root position. If you are working in chapters in ChessBase or Lichess, merge them into one tree before import.
2. Notes only on the student's side A White course gets notes on White moves. A Black course gets notes on Black moves. In practice the note is usually written after the opponent's move, because that is the position the student is looking at when they have to decide what to play.
3. Every student move gets a note Short is fine. The note has to make clear what move the student should play, either explicitly or implicitly.
4. One correct student move per position All branching in the tree comes from opponent moves, not from giving the student a choice. A White course is an e4 course or a d4 course, not both.

Chessreps is not a Chessable course

Both products can accept PGNs, but they use them differently. Chessable works well as an annotated tree students click through. Chessreps turns the tree into lines students play one at a time.

What to put in the tree

Write for the positions your students will see in their own games. Keep Lichess Opening Explorer open while you author and use it to decide which opponent moves to cover.

For each position where the opponent moves, cover the common Lichess responses first. If a common opponent move is bad, include it anyway and write the punishment. This is normal in a Chessreps course, including in the first few moves.

Include the must-know main lines too, especially when not knowing them causes the student to lose the opening. Skip rare opponent sidelines unless they contain a concrete tactical threat the student must know.

A normal course is 30-50 generated lines. More is fine. Count generated lines, not visible branches in ChessBase or Lichess.

A typical line is 12-15 moves, but stop when the student has reached a playable position. Six moves can be right when the position is settled. Twenty can be right when there is a concrete tactic or forced sequence the student needs to finish.

The whole course should be playable in one sitting. Memorizing it will take several sittings.

How to write notes

Notes go on student moves only. In practice, that usually means placing the note after the opponent move, because that is the position shown to the student right before they reply.

A note generally answers three things:

• What did the opponent do?
• What should we play?
• Why?

This is a guideline, not a template. Obvious moves can have very short notes.

Good notes

Black has played ...Nf6, attacking e4. Castle first. If Black takes on e4, Re1 hits the exposed knight.
Qxd4. Recapture the pawn.
Nf3. Develop and defend e5.
O-O. Castle. The center is about to open and the king on e1 will be exposed.

Bad notes

Best move.
An interesting move with rich strategic content.
The position is roughly +0.2 at depth 38.
Knight to f3.
[no note]

If the move is automatic, keep the note short. "Recapture" or "Only move" is enough.

Import early

Do not finish the whole tree before checking it. After you have two or three variations in the PGN, import it into Chessreps.

• Choose the side the student plays.
• Click through the PGN tree and confirm the moves look right.
• Click the "X lines" count at the top to open the generated lines.
• Skim the generated lines. This is what the student will be served.
• Click Play in the top right and play through several lines as a student.

Fix issues there and keep authoring. Re-import as you add material.

PGN shape examples

Good basic PGN

This is a small White course. White has one move at each White turn. Black moves create the branches. The notes sit where White will read them before moving.

[Event "Italian Game Starter"]
[Site "?"]
[Date "2026.01.01"]
[Round "?"]
[White "USER"]
[Black "Opponent"]
[Result "*"]

{Start with e4. We take the center and open lines for the bishop and queen.}
1. e4
e5 {Black mirrors us in the center. Develop Nf3 and attack e5.}
(1... c5 {Black chooses the Sicilian. Play Nf3 and keep the center flexible.}
2. Nf3)
2. Nf3
Nc6 {Black defends e5. Play Bc4 and start putting pressure on f7.}
3. Bc4
3... Bc5 {Black chooses the quiet Italian. Play c3 so d4 is ready next.}
(3... Nf6 {Black attacks e4. Castle first. If Black takes on e4, Re1 hits the exposed knight.}
4. O-O)
4. c3
Nf6 {Black attacks e4 again. Play d4 and challenge the center.}
5. d4
exd4 {Black takes. Recapture with cxd4 and build the pawn center.}
6. cxd4
*

Bad PGN

This is fine in a general study, but not in one Chessreps course. White has three first-move choices. Chessreps will ask the student to memorize all of them as one course. Pick one; if you want both e4 and d4, that is two courses.

[Event "Too Many White Repertoires"]
[White "USER"]
[Black "Opponent"]
[Result "*"]

1. e4 {King pawn repertoire.}
(1. d4 {Queen pawn repertoire.})
(1. c4 {English repertoire.})
*

Final checklist

• One PGN file, one tree, one root position.
• Notes only on the student's side.
• Every student move has a note.
• Every note makes the student's move clear.
• Every position where the student moves has exactly one correct move.
• Common opponent moves from Lichess Opening Explorer are covered.
• Common bad opponent moves are included with their punishment.
• Generated line count is in the 30-50 range, or higher if the opening needs it.
• Each line stops at a sensible point.
• You imported the PGN, opened the generated lines list, and played through the course.