I'd definitely want unit design (as well as torp design).  Was just giving the sort of daydream image that started me down this road.

The first thing that came to mind other than "Sounds awesome", was that there should be rules for both double-blind (As you described) and standard play, as it can be difficult for me to get more than one person over. Plus, the non-blind version would work for quicker play.

EDIT: Something that actually came up on SCN. YOu should be careful with a detection-based system, because there's always the possibility of "Well, looks like I can't play this time."

Secondly, a mechanic that comes to mind is the "Pressure threshold.": if the hull of a sub is weakened enough by weapons fire, the water pressure could cause damage to the sub as well. Of course, this largely depends on the depth that's applied to a particular battle.

I have to admit that I keep having second thoughts about going double blind.  I wanted part of the atmosphere to be like playing the old Red Storm Rising game by Microprose.  To be in a situation of, " I know he's got to be about there.  So I'll fire off a torp near there and let it go active and flush him."  But thinking it through I'm having to make some assumptions I'm not wild about.  No range mods for sensors for one.  And the playing area's going to be pretty sparse starting out.  And plotting for hidden units can be a real hastle.

The main issue I think is that instead of just the platform being responsible for all of the sensor work, the torps themselves should have a sensor rating to determine their actual chance to hit.  I'll try to post on outline version in a bit how I imagine sensor and combat working.

"Pressure Threshold"  I'm liking that idea.  If we built it into the construction rules for subs to be rated at various depths and as they take damage that rating drops.  Maybe linked to Hull Points or maybe via criticals.

Actually one thing I saw over at the SCN forum I found rather intriguing was to have units pre-plot movement at the beginning of the turn and forego initiative.  I could see something like that working well with your game proposal.

You could run the game on sheets of hex paper until units are detected then place them on the main board.  When sensor contact is lost, a position marker would be placed at point of last contact and plotting would continue as normal.  This would provide a continuity of play through the game while switching between detected and hidden states I think. 

Hull crush...if the hull has a strength rating and each certain amount of damage lowers this...with the rating equalling 100 feet of depth per point or some such number I can see pressure implosion occurring rather easily.  "popped him like balloon!"

RE: Detection...

A halfway point would be to not have movement double-blind, but require detection in order to attack a target...

I think that's where I'm falling toward right now.  Sensor rolls to generate a good enough firing solution over time.  Although you can fire with a lower solution and take a modifier on the to hit.

Ok.... here's how I imagine the detection side of things being handled in a non blind game.

Every sub has a Noise Rating with a basic value assigned to each hull.  It gets modified every turn by the speed at which the sub is moving, weaponry fired, etc.  Each sub then has sensor dice that they allocate to attempt to detect bogeys.  Every hit increases the firing solution versus that target.  That would mean having to keep track over time of the firing solution versus the targets tracked.  A sensor turn with no hits on the target would drop the solution down a level. 

And unless someone has a good real world or PSB reason for subs to be able to communicate with each other their firing solutions then each sub would be attempting to track targets independently. 

Torps would be the main weapons with each one stated out with Warhead, Speed, Endurance, Sensor and their own Noise Rating.  When a torp is launched it travels to a designated area and then goes active.  It starts rolling it's own sensor rating to acquire the target modified by the firing solution of the launching sub when launched.  (Unless it's wire guided.)  If it acquires a target it will close to hit unless it's shot down, spoofed or runs out of Endurance. 

Sorry if any of these seems meandering or not quiet well thought out.  I'm still thinking out loud at this phase.

Quite a fun little movie but a bet heavy on the philosphy side sometimes.

I think for a sub game pulsed movement is a must, increases tension. And stops the teleporting phenomen.

Use command points to determine the number of pulses.  So if a max. of 10 exists and you have four subs in combat with command ratings of 3, 5, 7, and 9 respectively they would perform actions 30%, 50%, 70%, and 90% of the turn respectively, conversationally speaking. 

It should keep things simple, intuitive, and give a great deal of meaning to having the more experienced officers and crews.

So a sub would move based on it's speed and the current pulse.  Say 10 pulses and speed 5 would move every other pulse.  But it would only be able to do an action based on it's command rating?  Is that where you're going googleplex? 

I never would have thought of that command rating idea.  It's brilliant.

Love it. Gonna steal it.