Fighting inside an asteroid

Doesn't it look peaceful...

Most SciFi wargames take place in a very terrestrial landscape, and tend to suffer from the terrain equivalent of the monster in the rubber suit effect. Now all this can be justified, after all why else would people (or aliens) be fighting over territory unless it was worth taking, which means it would have to be semi terrestrial at least.

So the idea of this post is to explore the possibilities of combat in a less terrestrial like environment, that of an asteroid habitat.

...we can soon fix that!

Asteroid habitats are made by hollowing out an enclosure within a largish (kilometre long) asteroid, spinning it along its axis for gravity and then terraforming the interior.

So there's a few issues you need to work out to wargame combat in an asteroid habitat. I'm going to work out some additional rules for Tomorrows War to deal with this and hopefully soon, depending on the outcome of the next few sessions of my Traveller Campaign, try out the rules in a game.

So here come my draft (and hopefully not too daft) rules...

The Asteroid

The inside of the asteroid will be a 6" x 4" table, rolled up so the two short edges are touching. Based on a ground scale of 1:500 this would give a cylindrical asteroid enclosure with a radius of 143m and a length of 600m.

Tomorrows War does not have a stated ground scale, but its obviously not 1:1 with figure height as that would mean that the unit cohesion distance (1") would be 2.5m. That's a little close for infantry spacing. At 1:500, this distance is 12.5m which is a little more realistic.

This asteroid is going to have a simulated gravity of 0.33G, this means that the surface is moving with a speed of 21.5m, spinning with a period of 41.8 seconds.

Rule 1 : Topology

The easiest way to model the interior is to say that the table surface is wrapped around the inside of a cylinder. If you move a unit off a short edge of the table, then it comes on at the other short edge. The long edges end in vertical cliffs and are impassable except by doors into the rocky shell of the asteroid, leading to the power rooms, living quarters and ship bays perhaps.

Rule 2 : Curvature

This may seem obvious, but as the inside is curved, units will be able to see over obstacles in certain directions. Obstacles will have a dead ground shadow as shown in the following diagram.

A unit at A can see over the building B to a certain extent, unit C is hidden but unit D is exposed. The length of the dead zone Z is dependant on the degree of curvature, the height of the obstacle H and the distance D from the obstacle. This only applies along the long axis of the table, looking along the short axis, any obstacle will block visibility completely.

This table gives the distance in inches of the Dead Zone (Z) for various distances (D) from the obstacle. The height H of the obstacle is in figure heights (based on 15mm miniatures).This is based on the 143m radius asteroid described above.

Distance D
Height H		1	2	3	4	5	6	7	8	9	10	11	12
	1	1	1	0	0	0	0	0	0	0	0	0	0
	2	4	2	2	1	1	1	1	1	1	1	1	1
	3	7	4	3	2	2	2	1	1	1	1	1	1
	4	9	5	3	3	2	2	2	1	1	1	1	1
	5	11	6	5	4	3	3	2	2	2	2	2	1

Rule 3 : The Coriolis Effect

The Coriolis Effect is caused by the rotation of the asteroid. Its effects will be felt in movement and shooting. Treat all movement in the asteroid as low grav (roll Troop Quality to move fast) but with a modifier of -1 on the roll, unless the units are used to the condition inside a rotating asteroid (home team advantage!).

The Coriolis Effect will also affect shooting: as the surface is moving then by the time your bullet gets there, the target will have rotated out of the way. In the case of this asteroid, if the round takes a second to get there then the target will have moved 21.5m. The following table shows the reduction in firepower based on range and speed of projectile.

Lasers	No effect
High Velocity Weapons	-1 FP per 6"
Medium Velocity Weapons	-2 FP per 6"
Low Velocity Weapons	-3 FP per 6"

Laser weapons are obvious. High velocity weapons are hypersonic weapons like gauss guns, high power sniper weapons etc. Medium velocity weopons are typical supersonic assault weapons. Low velocity weapons are zero G snub weapons, accelerator (rocket) rifles, bows and the like.

You can counteract the effect by using guidance and or advanced computerised sighting. Each of these reduces the negative effect by one level (so a guided rocket rifles with computerised sights would only be reduced by -1 FP per 6").

The FP reduction is off the total FP for the unit firing based on the majority of weapon types in the unit in question.

Rule 4 : The Light Cylinder

The asteroid may have a "Light Cylinder". This is a transparent, perspex like cylinder running along the axis of rotation. The purpose of the cylinder is to illuminate the interior of the asteroid. Mirrors bounce sun light down the cylinder which then illuminates the enclosure. The cylinder can also be used for artificial rain by sprinkling water from it.

This means that it blocks line of sight for any unit directly above it, so for the asteroid in question any unit 36 inches +/- 3 inches further up the table is blocked from view by the cylinder and/or its glow.

Rule 5 : Flying Things

I'm sure they'll be affected but right now I'm, not sure how.

Anyway all comments and suggestions welcome