[Ogre] Optional GEV rule: irradiated terrain

[David Morse]

This optional rule supercedes all spillover rules for a different system. 

Each hex has a radiation level, an integer typically between 0-12. 
Use those D12s you bought for recording the rubble threshold.  At the
beginning of the game hexes have radiation levels of 0 by default. 
For every non-AP, non-overrun attack directed into a hex, increase the
radition level of that hex by that many strength points.  At the end
of each player's turn, halve the radiation level of each hex, rounding
fractions towards 0.  At the end of its enemy's fire phase,  or
whenever moving into an irradiated hex, a unit undergoes a spillover
attack by comparing half the radiation level and applying it against
the D of the unit.

Example 1: a HVY is sitting around, minding its own business, when an
Ogre Missile (strength 6) comes out of the blue and slams into the
ground next to it.  At the end of the fire phase, the hex has a
radiation level of 6, so there's a radiation attack against the HVY. 
Strength 3 versus D3: 1-1, die roll is a 6, X which means D
(spillover), and the HVY is knocked unconcious.  At the end of the
turn, the radiation level drops to 3. During the HVY player's turn, he
sits around complaining about how much life sucks, and the radiation
level drops to 1.  During the opponent's turn, nothing happens except
the radiation drops to 0.  And finally the HVY recovers!

Example 2: three GEVs overrun a HVY sitting in a hex with a radiation
level of 4.  First each GEV takes a 1-1 spillover attack, and one gets
D'ed.  Then the HVY fires, killing another GEV.  The active GEV and
the cripple team up for a 1-1 on the HVY, and whiff.  The HVY smokes
the active.  The cripple cries into his beer.  The HVY finishes up the
cripple, and paints three kill stickers onto his hull...

Use the following new CRT for all non-overrun situations (gee I hope
you're reading this in a fixed-width font):

+---------------------+
| |1-2|1-1|2-1|3-1|4-1|
|-+---+---+---+---+---|
|1| - | - | - | - | D |
|-+---+---+---+---+---|
|2| - | - | - | D | X |
|-+---+---+---+---+---|
|3| - | - | D | X | X |
|-+---+---+---+---+---|
|4| - | D | X | X | X |
|-+---+---+---+---+---|
|5| D | X | X | X | X |
|-+---+---+---+---+---|
|6| X | X | X | X | X |
+---------------------+

(designers note: this is to decrease double-jeopardy of getting
disabled by a direct attack, and then getting double-disabled by the
irradiation - I guess the math work out more or less, though this
still sqews combat results a little towards X and NE and away from D).