Logic Masters Deutschland e.V.

The universe is a dark forest. Every civilization is an armed hunter stalking through the trees like a ghost, gently pushing aside branches that block the path and trying to tread without sound. Even breathing is done with care. The hunter has to be careful, because everywhere in the forest are stealthy hunters like him. If he finds other life—another hunter, an angel or a demon, a delicate infant or a tottering old man, a fairy or a demigod—there’s only one thing he can do: open fire and eliminate them. In this forest, hell is other people. An eternal threat that any life that exposes its own existence will be swiftly wiped out. This is the picture of cosmic civilization.

This puzzle is inspired by The Dark Forest written by Liu Cixin. It is one of my favorite sci-fi so far, and this puzzle is just my negligible tribute to the magnificent universe imagery presented in the novel

Ruleset without those fancy terms related to the novel

1. Normal sudoku rules apply

2. There is 1 radar cell in each box. Except for the two radar cells colored in grey which are not affected by all rules below, every radar cell indexes the relative octane number (refer to the example) of the closest not-grey radar cell from it that has not been indexed, and does not result in violating any other rules

The positions of the radar cells (including grey radars) follow the anti-queen rule. Two radars cannot index each other, and each radar can only be indexed once

3. The circles in the grid are the starts (big) and the tips (small) of arrows, and the tips are diagonally or orthogonally connected to the indexed radar. The trace of the arrows must be determined by the solver. Arrows cannot overlap

The circle of an arrow must contain the starting point, but the starting point does not necessarily make up the entire circle (i.e. you can also form a two-digit circle containing the starting point)

An arrow circle can only pass one orthogonally or diagonally connected cells of its belonging radar

4. Every arrow is colored with the same color as its belonging radar cell. The arrow must pass through all orthogonally connected cells of the radar cell that its belonging radar is indicated

5. The grid is covered by the fog, with some other constraints hidden

Accessing links:

CTC (white background)

CTC (black background)

PS: I personally recommend using the white background with better observation convenience

An example of relative octant index:

The cell marked by A represents the indexing radar, and the indexed radar must fall into any of the 8 octants centered in the A cell. The digit A itself is the index of the octant that the indexed radar locates

An example of arrows and radars:

The original ruleset (with references and terms)