Space Hulk Rules

[Blankhalo]

While doublek666 summaries the rules changes between 1st and 3rd editions very well, now I have had a few games, it's worth pointing out how this translates into differences while playing. The biggest difference is that it is much, much easier for a marine player to hold a perimeter. The new sustained fire bonus on overwatch (5+ instead of 6+) and the reduction in cost to clear jams means that if the marine player just holds back 2CPs then it is nearly impossible as the 'stealer player to break the perimeter. (Whereas in first with persistence and whole bunch of 'stealers you could break the perimeter). Two other factors help here too, the new 'guard' stance and the fact you usually have more more command points due the new ability to redraw the CP token if you don't like the first.
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We had one game where the Sargent with the thunder hammer and storm shield was on 'guard' protecting a key corridor. He must have mulched some 25 'stealers before one eventually killed him - it suddenly became the point of the whole game . Not sure of the mathhammer on this one but it is now very hard to break down a well set up perimeter.

[Commander Dante]

From memory of previous versions voluntary is good when you wouldn't be able to place all the models the blip contains should it be involuntary revealed.

In fact, it works like this (from 1st ed. rules):

"BLIP CONVERSION
There are two ways in which a Blip converts into
Stealers: voluntary conversion - when the Stealer
player converts the Blip - and involuntary
conversion - when the Marine player converts the
Blip.

Voluntary Conversion
A Blip counter can be converted into Stealers during
the Stealer player’s Action Phase. He converts the
Blip instead of Activating the Blip; if the Blip has
performed any action that Action Phase, he may not
convert it. Stealers can be Activated during the Action
Phase of the turn they were converted with a full
complement of 6 APs.

Involuntary Conversion
Marines cause involuntary conversion when they gain
LOS to a Blip. In involuntary conversion, the Marine
player converts the Blip to Stealers and places them
on the board; but the Stealer player gets to choose
their facing.

If a Marine gains an LOS to a Blip during the Stealer
player’s turn (if for instance, he uses CPs to blow
away a model which was blocking LOS), then the Blip
is involuntarily converted into models by the Marine
player. If the Blip has not yet been activated that
Phase; then all of the newly-placed Stealer models
can be activated as normal. If the Blip has already
been activated, than the Stealers cannot be activated.
Remember that a Blip cannot move into a Marine’s
LOS; however, the Stealer player can move a Stealer
which was blocking a Marine’s LOS, allowing the
Marine to gain LOS to the Blip. This would be
involuntary conversion and the Marine player would
place the Stealers.

How To Convert Blips
Turn the Blip counter over to reveal the number of
Stealers it represents. Remove the counter from play
and place the appropriate number of Stealers on the
map. Place the Stealers so that one Stealer occupies
the square where the Blip stood, and any remaining
Stealers are placed in empty squares adjacent to that
model.
In voluntary conversion, the Stealer player cannot place
his Stealers in a Marine’s LOS; in involuntary
conversion, the Marine player can place the Stealers in
or out of LOS as he wishes.
If there aren’t enough available squares to place all of
the Stealers, the excess Stealers are lost.
After the Stealers are placed on the map, the Stealer
player gives the Stealers any facing he wishes, even if it
was involuntary conversion and the Marine player
placed the Stealers."

Enjoy!