Here the planet rules Arthur and I came up with (Athur all but the last four!) If anyone thinks these will unfairly impact on their armies or unfairly boost another players army then post in the comments with your alternate suggestions. I thought a terrain list and board layout would help differentiate these worlds and mean that game experiences for different players didn't differ too vastly. When we have consensus I'll post up final rules for these.
Svarlbard: The Ice World
Native lifeforms: The Yeti
One piece of terrain chosen secretly, preferably by a neutral 3rd party or randomly if necessary, at the beginning of the game (must be outside both deployment zones) is the Yeti’s home. Any Unit that enters the terrain is attacked by the Yeti and takes D3 st5 AP- hits. However the nest is somewhat sheltered from the elements and so they count the result of the blinding ice storm as being one category lower than it is. I.e. if a 5-9 is rolled it would count as a 1-4 for a unit in the Yeti’s den.
Blinding Ice Storms:
On each GAME turn starting with the first roll a D6 and add the turn number, consult the chart below for the result which lasts until the next game turn when a new roll is made.
1-4 the cold penetrates armour right to the bone and troops grumble about the weather but there are otherwise no ill effects
5-9 the beginnings of a snow storm, any infantry move as though in difficult terrain.
10-12 the planet seems almost to be trying to rid itself of meddling interlopers, on top of counting all terrain as difficult (even vehicles) all troops count their BS as being 1 lower than normal (to a minimum of 2) and must test to see if they can make out any enemy they wish to shoot or charge by rolling 2D6 and multiplying the result by 3, if they are unable to see their target they cannot shoot or charge that turn.
Gehenna: World of Lava
Among the only life that survives here is the monstrous Salamander, these can be found wandering the wastes hunting for food or circling their nests to protect their eggs.
Each Game turn roll 2D6 for each unit on the table including those locked in combat (the noise and movement attracts the salamanders) if any unit roles a double they have been attacked by a wandering Salamander and take 1D6 St5 AP – hits as the salamanders attempt to bite them before being driven off.
Whenever a unit enters terrain for the first time roll a D6, on a 1 it is a nest and the salamander will spit acid at the unit and any subsequent units that enter the terrain each turn, until the unit leaves the terrain completely, to drive it from the nest doing D3 St3 AP 3 hits from the salamanders fearsome breath. However the salamander eggs have incredibly thick shells and so any cover saved provided by a nest is increased by 1. (So 3+ cover save?-Chris)
Any water feature on Gehenna is counted as lava and therefore is dangerous terrain instead of difficult.
Alvarak Prime:
Although a civilized and not a hive world Alvarak’s defences are based around its many cities meaning that battles on this planet take the form of brutal sieges. Battles fought here use the city board.
However it is possible to launch raids onto the planet this is done by challenging someone to a game as normal but making it clear it is only a raid. After the battle is fought the winner may remove a tile belonging to the loser, however he may not add a tile of his own, this represents a loss of resources but the attacker has sent enough troops to hold any territory himself, or if the defender wins and removes an enemy tile it represents the resources lost in launching the raid which are not recovered due to the loss. (This raid still presumably still counts as one of your three attacks? Can it only be made if you control a tile on the planet already?)
Raids of this kind may only be launched on Alvarak prime. Other planets are either not as widely settled and so can keep resources more concentrated in fortified areas immune to these kind of raiding tactics.
Concentra:
This planet is a hive, the spaces between the cities are a hell to rival any death world and battles fought here are brutal affairs where snipers and insurgents await round every corner. For games set here use the city of death stratagems.
Malmoral
This is a planetwide hive of degenerate gangs and has frequent riots. Fight on the city board.
Rubble and Wreckage: Infantry moving through the open streets suffer -1 movement during the shooting and assault phases.
Gang fortified position: Each player may nominate a single building on the board to be given a gangland makeover. Those buildings give infantry inside a 3+ cover save. A player does not have to nominate a building if they do not wish to.
Epsilon 0111
Own table with assorted scatter terrain.
Table layout: Manufactorum tile and generator tile on diagonally opposite corners with flat tiles in the centre with pipeline running through the centre line of the board between deployments. Scatter terrain to break up the central open tiles.
Oppresive heat: Infantry units running or vehicles moving flat out suffer -1 to movement.
Heat Haze: When firing at units over 24 inches away the unit counts as having a 6+ cover save against that shooting that stacks with cover saves other than 'Jink'.
Manufactorm tile:
Counts as an objective worth 1VP in any objective games if held on the final turn. The objective is the whole tile and is considered held by any unit or multiple units from one army standing upon it and is contested by any enemy unit also on the tile. Units with objective secured will hold the objective if contested by an enemy unit without it as normal.
Ammunition Dump: One unit of controlling player on the tile may re roll to hit rolls of 1 and reduce any scatter by 1inch.
Generatorum tile:
Counts as an objective worth 1VP in any objective games if held on the final turn. The objective is the whole tile and is considered held by any unit or multiple units from one army standing upon it and is contested by any enemy unit also on the tile. Units with objective secured will hold the objective if contested by an enemy unit without it as normal.
Defensive shielding: One unit of controlling player on the tile gains a cover save of +5 that can only be improved by the heat haze rule.
Memphis
A dense jungle makes navigating this planet a logistical challenge. Mysterious complexes wallow in the thick mud and brackish water at their top breaking through the jungle canopy. Occasional ruins mark humanities failed attempts to settle here. In such a death world even the plants seem bent on the consumption of interlopers.
Terrain list and table layout: Necron tomb complex tile and five realm of battle tiles, four hills and one flat with the hill piece placed to form one large plateau in the centre. Three forests, two on the hills one on the flat. 1-3 Marshes. 1-2 assorted ruins.
Table rules.
Forest are dense 4+ cover save for infantry but -1 movement.
Mud and brackish water. The unstable nature of the surface combined with its sticky texture means all vehicles (skimmers/walkers/etc. included!) without the move through cover rule.
Swamps are dangerous terrain to infantry.
Necron Tomb.
Counts as an objective worth 1VP in any objective games if held on the final turn. The objective is the whole tile and is considered held by any unit or multiple units from one army standing upon it and is contested by any enemy unit also on the tile. Units with objective secured will hold the objective if contested by an enemy unit without it as normal.
Mysterious Weaponry: If held then the first enemy unit to enter the tile on a turn will take D3 S4 AP- hits when it enters. If it is a vehicle instead it stops as soon as it touches the tile and cannot move further this turn.
Venus man traps:
3 face down counters are placed on the three forests. The first time an infantry unit enters a forest flip the token. If the man traps are revealed and the forest is considered infested. Any infantry units moving through (within/into/out of) an infested forest takes a single S5 AP3 hit each time they move. If a to wound roll of 1 is rolled then the squad member has defended themselves and killed the man trap remove the infestation counter.
Pyreus "Roads"
Realm of battle board with flat tiles in the centre and hill tiles with the hill sections pointing outward. Three forest tiles around the short edges of the board. Skyshield landing pad in the centre of the board. Sentinal lifter dropper unit placed towards one of the short edges of the table beside the pad. Three buildings and assorted crate scatter terrain to break up the centre.
Compacted earth: Infantry not in terrain and not on hill sections gain +1 to their movement in the movement phase.
Commercial Landing pad:
Counts as an objective worth 1VP in any objective games if held on the final turn. The objective is the whole building and is considered held by any unit or multiple units from one army standing upon the raised pad area and is contested by any enemy unit also on it. Units with objective secured will hold the objective if contested by an enemy unit without it as normal. Infantry units count as moving three inches to climb any leg ladder of the pad. A non-vehicle unit standing above (within 2) of any leg will prevent movement up that leg.
Constant Trade: Any player holding the landing pad will gain +1 to their reserve rolls.
Defensible position: Infantry on the pad gain a 6+ cover save from any shooting attack from units not on the pad.
The sentinal lifter dropper is a walker vehicle with AV 11/11/11 and 2HP with move through cover and 2 attacks with a S10 Unwieldy weapon that gains +1A on the charge. In any players shooting turn that player may 'aim' at the sentinal with any unit within 12. The frightened driver will take your orders until someone scares him again. The unit can be shot and assaulted as normal if desired (boo hiss!). If not controlled the unit will remain still and hope to remain unnoticed however it will attack back in combat if assaulted.