Click Import Game to load a saved game — choose a .rgn file from the Raumschach client, or switch to the Paste tab and type or paste a move list directly. Tag headers ([White “…”] etc.) are parsed automatically and shown above the board. To start from scratch and play out a position interactively, use New Game.

In Move mode, click any piece belonging to the side to move. Legal destination squares light up with gold dots; occupied capturable squares show a gold border instead. Sliders (Rook, Bishop, Unicorn, Queen) shade the path they travel. Click the destination to execute the move. Click the same square again, or any empty non-destination square, to deselect. When a pawn reaches its promotion rank, a picker appears — choose any piece.

From any position you can play alternative moves to branch the tree. Variations appear indented in parentheses in the move list below the main line, and you can navigate into them by clicking or with the arrow keys. The text box below the boards attaches a note to the current position; positions with comments show a small ◆ marker in the move list.

Click Setup (or press S) to enter Setup mode. A toolbar appears below with side-to-move buttons and Done/Cancel controls.

Click any square to open the piece picker. Choose a colour and piece type to place it; click Clear this square to remove a piece already there. Unavailable options appear dimmed — these include parity-locked squares for Bishops and Unicorns (each can only occupy squares of the parity class, (level + rank + file) mod 2, they were first placed on) and any piece type whose count ceiling has been reached.

When finished, select the side to move, then click Done. Both Kings must be present and the side not to move must not be in check. The position becomes the root of a new analysis tree. Cancel discards all changes.

Switch to Draw mode (button or D). Click a square to toggle a colored highlight on it. Click and drag — or right-click and drag — from one square to another to place an arrow between them; repeating removes it. Choose gold, green, red, or blue from the color swatches. Clear (or Esc) removes all annotations from the current position.

Toggle Raumcapa with the Engine button. It evaluates the current position and displays a score bar (further right = White advantage), a numeric score in pawns, a phase readout for each side (Opening / Middlegame / Endgame), and a platinum best-move arrow on the board. The Strength selector sets how reliable its analysis is, from Boy (a random legal move, no evaluation) up through Prodigy, Challenger, and Champion to The Machine (noise-free, fully deterministic best play) — the default.

With the engine on, toggle Etiology to see the reasoning behind its recommended move, not just its score. Raumcapa selects candidate moves by named positional principles and scores them by named evaluation terms — documented in full at raumcapa.html — and Etiology surfaces both: which principle nominated the move, and which terms made up its final score, ranked by size. A Compare alternatives toggle shows the same breakdown for the move's closest rivals, so you can see why one was preferred over another. Because Raumcapa has no search tree to summarize and no learned weights to interpret, this is the engine's actual calculation, not a generated explanation of it.

With the engine on, navigate through a loaded game to see how well each move was played. As you step to each position, Raumcapa compares its best available move to the one actually played; the difference in evaluation — the centipawn loss — determines the flag shown in the move list:

?! Dubious — 30–99 cp loss   ? Mistake — 100–299 cp loss   ?? Blunder — 300+ cp loss

Hover a flag to see the exact loss. A flag appears only after the engine has analysed both the preceding position and the current one, so they accumulate as you step forward and backward through the game.

3D View — perspective view of all five boards stacked; arrows are hidden in 3D mode.
Undo — steps back and discards the last move from the tree (also Ctrl+Z).
New Game — resets the board to the starting position and clears the tree.