Master Database

The Explorer panel shows opening statistics for the current board position. It is available on both the Board page and the Repertoire Builder. It has two tabs: Master DB (master game database) and My Games (your personal game collection).

For each candidate move from the current position, the Explorer shows:

• Move popularity — total games in which this move was played
• W/D/L bar — colour-coded win/draw/loss breakdown
• Performance % — (wins + 0.5 × draws) / total
• Average Elo of players who chose this move

Below the move table, a list of example games is shown. Click a game to view its full PGN on the Board page.

Recommended data source

The recommended collection is Lumbra’s Gigabase — a freely available, regularly updated compilation of over-the-board games from professional and amateur tournaments. It covers millions of games and is updated periodically.

Importing a master database

1. Go to Settings → Master Game Database.
2. Click Select PGN Files.
3. Choose one or more .pgn files using the standard OS file picker. There is no folder picker — if you want to import an entire directory, select all the files within it.
4. Masterboard shows the selected files with estimated game counts and import time. Review the list and click Start Import.
5. Import runs in the background with a live progress bar. You can continue using the app while it runs.

Tip

Lumbra’s Gigabase comes as separate OTB and Online files. Import only the files you want — the source is inferred from the filename and controls the All/OTB/Online toggle in the Explorer panel.

Replace vs. append

Once a database is indexed, the Settings section shows two import options:

• Import More Files — appends games from additional files to the existing database. Duplicate games are detected and skipped.
• Replace Database — wipes the existing database and reimports from scratch. Use this when you want to start over with a different dataset.

Import provenance

After importing, the Settings page shows a summary line such as:

1,940,000 games from 3 files indexed · last imported 2026-04-07

Hover over this line to see the list of source filenames. This helps you track which files are in the current database, especially after multiple append imports.

OTB/Online source toggle

The Explorer panel’s Master DB tab has an All / OTB / Online filter. The default is OTB. Source is inferred from the PGN filename at import time — Lumbra’s Gigabase files include _OTB_ or _Online_ in their names. If your PGN files do not follow this naming convention, all games are imported as unknown source and appear under All.

My Games tab

The My Games tab queries your personal game collection using a local position index built incrementally as games are imported. Filters are available for folder, collection, and player name.

In the Repertoire Builder, clicking any move row in the Explorer panel adds that move directly to the repertoire at the current position as an opponent response.

Repertoire tab

The Explorer panel has a third Repertoire tab alongside Master DB and My Games. It shows the moves you have prepared at the current position across all your active repertoires — without having to open the Repertoire Builder.

The Repertoire tab is available in the same three locations as the other Explorer tabs:

• Board page — check your preparation while reviewing a game
• Repertoire Builder — see how the current position is covered across all repertoires, not just the one you are editing
• Reports view — verify opponent deviations against your own preparation

Theory diversion detection uses this same repertoire data. When you step through a game on the Board page, any move where you (or your opponent) deviated from your prepared lines is flagged automatically, showing the expected move alongside what was played.