So, working up an alpha-test of the Adeptus Titanicus card system that I recently figured out, one where players design decks, and play hands each turn by selecting which of four types of information on the card they want to buy with other cards in their hands. The four types of information include:
Of these types, specific instances include:
Walk (See Gressal Systems)
New Heading (see Gressal Systems)
Halt/All Stop/Lock (see Gressal Systems)
Kick (see Gressal Systems)
Acquire Target (see Auspex)
Arm Weapon (see Weapon)
Fire Weapon (see Weapon)
Punch (see Titan/Weapon)
Raise Shields (see Void Shield Generators)
Reorient Shields (see Void Shield Generators)
Extend Shields (see Void Shield Generators)
Silent Running (see Void Shield Generators)
Tactical Inspiration (See Crew)
Strategic Inspiration (See Crew)
New Orders (Dump Hand for new victory conditions - See Mission?)
Damage Control (See Crew, Autorepair, etc)
The number of cards per hand is defined by the Titan's crew. The Captain/Princeps/etc gives three cards, and each additional officer adds one each. Crew can be lost to damage. A Warlord Titan, for example, might have seven cards per hand where there is a Princeps, two Moderati, a Magos, and an Enginseer. Things like the Titan's Auspex, Weapons, Gressal Systems, Void Shield Generators, Crew and so on will define the cost of card results. So a Titan will have a different cost to arm a Plasma Destructor than to arm a Multi-Missile Launcher, for example.
Systems on some sort of record sheet would therefore include a cost in cards to activate using cards, and a damage-grading system to track damage inflicted and repaired. Offhand I'd go with Light Damage, Heavy Damage, and Overkill as sequenced damage boxes with x number of light damage accumulating to be heavy damage, and eventually overkill.
The cards essentially cover active things like managing defense through shields, position, and damage control, and the Titan itself does passive things like maintaining a particular course and speed, maintaining damage states, crew, and so on.
Weapon-wise I think that the number of shots, and perhaps the power of the shots, is going to be limited by the weapon having an ammunition cost that can be met (and occasionally exceeded). So munitions, range, power, and rate of fire something like multiple weapon profiles in Warhammer 40,000. A Volcano Cannon or Heat Lance is going to have one profile for some set munitions cost, while stuff like Vulcan Megabolters are going to have a graduated profile of something like one card per shot, and Plasma allowing players to increase both power and shots, and maybe take light damage (disengage safeties!) instead of spending cards.
Power would be something like: 'greater than is light damage, greater than 2x is heavy damage, greater than 3x is overkill'. Acquring a target will cost some minimum with increased 'resolution' for targeting more important parts, with damage spilling over from parts. So a Warhound might take a Volcano Cannon to one of its weapons, and any overkill might cause light or heavy damage depending. I think having light damage count as friction against armour works for this.
In terms of gaming, the random element won't be whether you manage to hit, wound, or save with your Titan, or inflict so many points of damage, as whether you can combine or chain the cost of Acquiring the right part of the target, arming the right weapon, and shooting it at the right time knowing that your opponent is trying to do the same thing to you while also weighing defensive measures.
Defense-wise, you can take shots against shields, re-orient shields to take more/harder shots from another direction, or lose the protection to jam your opponent's auspex and increase the difficulty in acquiring a target. You can attack their gressal systems to prevent them from getting into an advantageous position, like getting a cover bonus or some such, or you can attack their weapons to minimize their ability to land a killing blow.
What I don't want is Titans simply closing the distance and slugging it out. Titans should be able to use active defensive measures, weighed against their active attack options, as well as tanking damage and hoping they get lucky. That's the theory, anyways.
Which means a Titan, or an Imperial one at that, has the following systems:
Crew (Command, Control, and Communications)
Gressal (Motive systems)
Weapons (Munitions, Range, Power, Rate of Fire, Special)
Void Shields (Holoshields, Power Fields, etc)
Auspex (Sensors, whatever)
Auto-Repair (not strictly necessary, but additional or upgrade systems might be interesting)