Spaceships

Spaceships is a three-dimensional variant of Battleships[1] (with which the reader of this explanation is expected to be familiar) played in a 5x5x5 arena. It is intended to be played using its own `simultaneous attack' rule.

1. Arena

The arena is a cube measuring 5 units on each side, which is divided into 125 unit cubes called `cells'. The three mutually perpendicular edges of the arena are indexed RED-YELLOW-GREEN-ORANGE-BLUE (abbreviated R-Y-G-O-B), v-w-x-y-z and 1-2-3-4-5. Cells are identified by unambiguous triples. There is no convention as to the handedness of these axes as it doesn't matter. The arena is most conveniently drawn as 5 grids, RED--BLUE, each labelled v--z along one edge and 1--5 along the other. The arena does not wrap.

2. Fleet

Each side has a fleet consisting of 5 ships, each of which occupies a characteristic set of cells. They are:

Heavy scout (2 adjacent cells) or light scout (1 cell).
Missile destroyer: 3 cells in a line.
Flying saucer or patrol cruiser: 4 cells as a 2x2x1 sqaure or a 4x1x1 line, respectively.
Kill cruiser: 6 cells in a 3x2x1 plate.
Death star: 8 cells, each cell having at least 2 neighbours in the death star; the whole death star must either contain a 2x2x2 cube or a 3x2x1 plate. For non-flat plate-based death stars the two extra cubes form the `bridge'.

Ships may not be placed diagonally. There are no restrictions on how close togehter ships may be placed, provided they don't overlap. A side is not told about the composition of the enemy fleet.

3. Turns

The game is played using simultaneous attacks. Each side writes down sealed orders for their shots, which are exchanged with the enemy (or read out, if the players trust one another). The hits are announced when the orders are revealed. All shots are considered to have been launched and unstoppable before any damage on the vessels firing them is incurred; that is, shots launched by a vessel destroyed in the same turn still count.

There is no requirement for a side to fire all or even any of the shots available to it. These are the kinds of shot:

3.1. Conventional strikes

A conventional strike hits a single cell. A conventional strike may be launched by any ship for every distinct pair of (non-diagonally) adjacent undamaged cells it occupies. Thus an undamaged kill cruiser can fire three shots but a destroyer only one. The death star is an exception: it can launch only one conventional strike per turn, but it can continue to do so so long as it exists.

3.2. Beam weapon

The death star also has a beam weapon. The beam weapon hits three adjacent or diagonally-adjacent cells. In order to fire a beam weapon the death star must have two adjacent or diagonally adjacent undamaged cells which lie in a line parallel to the line in which the target cells lie. The target cells do not have to pass through or start from the death star. The beam weapon can be fired once per turn, if the death star has sufficient remaining cells. If the beam weapon is fired diagonally and hits with both the end cells then it burns out and may not be used in future turns.

3.3. Missiles

The destroyer carries three missiles in addition to its conventional weapon, one for each of its cells. The destroyer may fire one missile in each turn. The missile is indistiguishable from a conventional strike to the enemy. Which cell it was fired from must be noted, but kept secret from the enemy. A hit on a cell containing a missile causes it to explode, destroying the missile and any adjacent cells in the destroyer.

3.4. Kamikaze strikes

When a ship can no longer use conventional weapons or missiles it may engage in a kamikaze strike, by sacrificing a cell in order to launch a single shot. The enemy is able to identify the number of kamikaze strikes launched and their cells of origin.

3.5. Scans

The light scout and heavy scout each carry a scanner, which may be used until the ship which carries it is destroyed. A side with at least one scanner can scan as many cells as cells belonging to their own ships were destroyed in the last turn, or scan one cell in the first turn or if none of their cells were destroyed. A scan reveals whether a cell contains a ship or not, but not what kind of ship.

4. Effects of fire

As in conventional Battleships, when a vessel is completely destroyed the fact must be reported, including the type and location of the ship, to the enemy. However, additionally, when a vessel is completely destroyed, its enemy must reveal flashcube data for the corresponding cells in its own arena. This includes the types (and identities, if they have several ships of a type) of any ships present and whether those cells have been destroyed (but not whether any missiles have been fired).

5. Victory

The game ends when one side's fleet is completely destroyed, or after a turn in which a side could not have done anything except launch kamikaze strikes or scans and did nothing but scans.

Each side scores a point for each of their own ships' cells which is intact at the end of the game. The side with the highest score is the winner.

5.1. Matches with cumulative points

A match may be played by totalling the points scored by each side in a succession of games. The winner may be the first side to a certain number of points, or the one with most points after a certain number of games, as decided before the start of the match.

5.2. Matches with resources carried through

If decided before the start of a match, each player counts up the number of cells left intact in their fleet. These are reformed into new vessels and added to the nomal fleet. In addition to the standard types of vessel they players may also choose to build gunboats:

Light gunboat: a light gunboat occupies one cell, and carries a missile.
Assault gunboat: an assault gunboat occupies two adjacent cells, and carries two missiles.

The number of cells in the new vessels must be equal to the number of cells carried through from the previous game, except that a building a scout (heavy or light) requires 3 of the carried through cells. Note that several scanners do not provide multiple scans; they merely make it more likely that at least one scanner will survive.

6. Leftover/optional rules

These rules were in earlier variants of the game and may still be playable. If they are to be used this must be negotiated in advance.

6.1. Hypothetical hits

If the usual rule would result in a draw, the sides count up the number of hits they would have scored in the last turn if the enemy had not launched any kamikaze strikes; the side with the greatest number of such hypothetical hits is declared the winner.

6.2. Scoring by hits

A side's score is the number of hits they scored during the game, plus the number of strikes they made on cells from which kamikaze strikes were launched or which were destroyed by exploding missiles in the same turn. Cells simply destroyed by exploding missiles do not count.

6.3. Restrictions on composition of ships from carried over resources

A player must use carried over resources to build ships according to one of the two tables below. For 9 or more cells, the cells required to make one of the largest kind of vessel are made into such a vessel and then the process is started over.

7. Acknowledgements and copyright

These rules were derived from the original ruleset by Sion Arrowsmith.
Copyright (C)1997 Sion Arrowsmith.
Copyright (C)1997 Ian Jackson.
Released under the terms of the GNU General Public Licence.

explanation of the Spaceships rules, version 2.6/1.0
Ian Jackson / ijackson@chiark.greenend.org.uk.

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