Sunday, August 18, 2013

Spaceships/JC: An Example Combat

There was recently a thread on the SJ Games forums asking for turn by turn examples of GURPS Spaceship combat. As seems predictable for all forum threads involving Spaceships, it turned into an obtuse argument about overpowered missiles and underpowered point defense but never actually delivered a turn by turn space combat.

Since I'm too sick to go gaming tomorrow, I'm going to write up an example turn by turn combat, using the Jovian Chronicles conversions I recently did. Given that the designs are horribly unoptimized for GURPS Spaceship combat, I suspect this might actually work better than doing a fight between a bunch of missile boats with low acceleration, high delta-V, and plenty of missile defense.

After running this combat, I redid some the designs slightly and reran the combat example. The second version is much more interesting, and much longer.

I'm trying to run these examples without any house rules. I'm not doing a perfect job of that, though. One issue is that technically, a single pilot/gunner can't fire two different weapons (GSS1 p53). I don't consider it at all abusive to let the pilot/gunner use both his main weapons and his point defense weapons at the same time, with appropriate multi-tasking penalties, and I didn't notice that rule on my first read through. I'm not about to go back through these examples and add a semi-competent AI gunner, but you can do that mentally if it really bothers you.
Thanks to the eagle-eyed readers of the forum and on the comments below who pointed out my mistakes. It's a learning experience and I welcome the feedback.

Scenario: Recovering the Floater

A flight of 4 Syreens have launched from their carrier on a rendezvous course with the drifting Mule freighter Carolina on my Thoughts. The Carolina has a Jovian Floater in its holds, and the CEGA would like another sample of this strange, extra-terrestrial life form. Meanwhile, a flight of 3 Pathfinders have launched from their carrier for the Carolina. Comm signals are established; words are exchanged; threats are made; and then someone on the CEGA side gets authority to go weapons free and a fight starts.

Special Rules and Command Orders

Objectives: Both sides want to recover the floater, which ways less than a ton and can be carried by any exo-armor with working arms. Either side wins if an exo-armor manages to pick up the floater, burn at least 1 mps of delta-V afterwards, and take 3 rounds of Retreat or Evasive maneuvers afterwards. Destroying the floater is automatically a tactical loss for the side that destroyed it.

The floater is in the Carolina's cargo bay. After rendezvousing with the uncontrollably drifting ship, it takes a Syreen with both arms working a total of 5 rounds of Ready maneuvers to tear through the hull; a Pathfinder can do it in 2 rounds with both arms working or 1 round of attack actions using a plasma lance. Multiple exo-armors can work together.

Retreating: Although both sides would like the floater, there are more floaters available and this is not a fight to the death. Any exo-armor that is damaged below 0 HP must take a Retreat maneuver (if possible) on its next action and cannot make attacks as long as it is capable of Retreating. Enemy exo-armors will not fire on a heavily damaged exo-armor that is Retreating and not firing (or that has a destroyed engine or no fuel left and is not firing as it uncontrollably drifts away). The only exception is any exo-armor fleeing the seen with the floater: enemy exo-armors can't fire on it, but they can attempt to rendezvous with it and steal the floater.

Opening Turn: Both the Jovian and the CEGA pilots are aware that a fight is about to break out when the CEGA pilots get the order to fire. So although both sides are nominally engaged in Controlled Drifts toward the Carolina and the Jovians wouldn't get Dodges against CEGA attacks on the first turn, the Jovians can perform some minimal thrust in response to CEGA maneuvering and Dodge at no penalty, though they do get -4 on maneuver contests. Similarly, both sides have power allocated to all their energy weapons and are taking Aim and Wait (Point Defense) maneuvers on the turn before the fight starts.

The CEGA pilots are in formation with each other and must attempt to stay in formation with at least one other pilot at all times; the Jovian pilots are not in formation and may maneuver freely.

All of the CEGA exo-armors will go before any of the Jovian exo-armors.

Turn Length and Scale: None of the ships have less than 0.05G+ of acceleration, more than 10G+ of acceleration, more than 5 mps of delta-V, or many weapons that reach past Short range. The best scale is Close Scale and the best Turn Length is 1-minute per turn.

delta-V reserves: For simplicity, the Pathfinders have 5 mps of delta-V and the Syreens have 3.5 mps of delta-V. It takes 1G and 0.3 mps to get a +2 acceleration bonus, 2G and 1.2 mps to get a +4 acceleration bonus, and 3G and 1.8 mps of delta-V to get a +6 acceleration bonus. The rapid increase in delta-V reflects the doubled fuel consumption for high thrust operations.

Skill Levels: The Jovians have Pilot-14, Artillery/Gunner (Whatever)-14, and all other space related skills at 13. The less trained CEGA pilots have Pilot-14, Artillery/Gunner (Whatever)-13, and all other space related skills at 12.

Play of the Encounter

CEGA Round 1: The CEGA high command gives the weapons free order and the attack starts. The flight commander knows the flight characteristics of her exos and those of her enemies; she'd prefer to stay at a distance and hammer them with missiles. They'll try to destroy a single Pathfinder with missiles this turn, or attack a second one if the first is destroyed before the third Syreen acts.

Each Syreen on its turn declares a three action multi-tasking penalty, and makes a Piloting task to perform a Closing maneuver against Pathfinder 1, a Gunnery task to perform an Aim and Attack with their CHS-4 missiles, and a Gunnery task to perform a Wait (Point Defense) with their ACDLS Screen.

Syreen 1 attempts a Closing maneuver against Pathfinder 1 and expends 0.3 mps of delta-V at 1G. She then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -2 for the multitasking penalty, netting a 6 against a 13 (MoS 7). The Pathfinder rolls against Pilot-14, at -4 for minimal acceleration bonus, +0 for the Pathfinder's Handling, and -1 for his multitasking penalty, netting a 14 against a 9 (MoF 5). Syreen 1 chooses to advantaged, firing at Pathfinder 1's rear hull, and at Long range.

She then releases a single CHS-4 missile at him. She has Gunner-13, -2 for multi-tasking, +5 for her target's size, +2 for her missile's sAcc, -2 for the Pathfinder's ECM array, -6 for 10 mps of relative velocity, and +4 for proximity detonation, rolling a 10 vs an effective 14 and achieving a hit. The Pathfinder opens up with its 652A particle cannon as point defense, using a single shot of the 3 available, and rolls a 9 against Gunner-14, +0 for target size, -3 for sAcc, +0 for Point Blank Range, +2 for a two-arm braced gun, and -1 for multitasking (net skill 12) and a hit.

Syreen 2 attempts a Closing maneuver against Pathfinder 1 and expends 0.3 mps of delta-V at 1G. He then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -2 for the multitasking penalty, netting a 12 against a 13 (MoS 1). The Pathfinder rolls against Pilot-14, at -4 for minimal acceleration bonus, +0 for the Pathfinder's Handling, and -1 for his multitasking penalty, netting a 10 against a 9 (MoF 1). Syreen 2 chooses to advantaged, firing at Pathfinder 1's rear hull, and at Short range, having unfortunately broken formation with his flight leader.

Nevertheless, he then releases a single CHS-4 missile at Pathfinder 1. Syreen 2 has Gunner-13, -2 for multi-tasking, +5 for his target's size, +2 for his missile's sAcc, -2 for the Pathfinder's ECM array, -6 for 10 mps of relative velocity, and +4 for proximity detonation, rolling a 10 vs an effective 14 and achieving a hit. The Pathfinder opens up with its 652A particle cannon as point defense, using a single shot of the 2 remaining, and rolls a 13 against Gunner-14, +0 for target size, -3 for sAcc, +0 for Point Blank Range, +2 for a two-arm braced gun, and -1 for multitasking (net skill 12) and a miss. Pathfinder 1 desperately dodges, rolling at against Piloting/2 (a 7), +0 for his handling, +1 for a 1 minute turn, +1 for defensive ECM, getting an 11 versus a target of 9. The missile explodes in the distance, doing 6dx5 cr for a total of 103 d-damage against rear hull location 3, the fusion torch. dDR is 14, so 89 d-damage penetrates, reducing Pathfinder 1 to -3xHP and destroying his engine. His fuel tank is also damaged in the attack. Pathfinder 1 makes 3 HT checks against destruction, rolling a 6, a 10, and an 11, and somehow survives. He is certainly out of the fight.

Syreen 3 is heartened by the destruction of the enemy flight leader and switches his attacks to Pathfinder 2. He starts by attempting a Closing maneuver against Pathfinder 2 and expends 0.3 mps of delta-V at 1G. He then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -2 for the multitasking penalty, netting a 10 against a 13 (MoS 3). The Pathfinder rolls against Pilot-14, at -4 for minimal acceleration bonus, +0 for the Pathfinder's Handling, and -1 for his multitasking penalty, netting a 16 against a 9 (MoS 7). Syreen 2 chooses to advantaged, firing at Pathfinder 1's rear hull, and at Long range. He's has also broken formation with both of the previous Syreens.

Nevertheless, he then releases a single CHS-4 missile at Pathfinder 2. Syreen 3 has Gunner-13, -2 for multi-tasking, +5 for his target's size, +2 for his missile's sAcc, -2 for the Pathfinder's ECM array, -6 for 10 mps of relative velocity, and +4 for proximity detonation, rolling a 12 vs an effective 14 and achieving a hit. The Pathfinder opens up with its 652A particle cannon as point defense, using a single shot of the 3 remaining, and rolls a 7 against Gunner-14, +0 for target size, -3 for sAcc, +0 for Point Blank Range, +2 for a two-arm braced gun, and -1 for multitasking (net skill 12) and a successful interception.

Syreen 4 follows after Pathfinder 2, attempting a Closing maneuver and expending 0.3 mps of delta-V at 1G. She then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -2 for the multitasking penalty, netting a 6 against a 13 (MoS 7). The Pathfinder rolls against Pilot-14, at -4 for minimal acceleration bonus, +0 for the Pathfinder's Handling, and -1 for his multitasking penalty, netting a 5 against a 9 (MoS 4). Syreen 4 wins the contest by 4 and chooses to advantaged, firing at Pathfinder 2's rear hull, and at Short range, leaving the entire Syreen formation in shambles.

Regardless, she then releases a single CHS-4 missile at Pathfinder 2. Syreen 4 has Gunner-13, -2 for multi-tasking, +5 for his target's size, +2 for his missile's sAcc, -2 for the Pathfinder's ECM array, -6 for 10 mps of relative velocity, and +4 for proximity detonation, rolling a 12 vs an effective 14 and achieving a hit. The Pathfinder opens up with its 652A particle cannon as point defense, using a single shot of the 2 remaining, and rolls a 13 against Gunner-14, +0 for target size, -3 for sAcc, +0 for Point Blank Range, +2 for a two-arm braced gun, and -1 for multitasking (net skill 12) and a miss. Pathfinder 1 desperately dodges, rolling at against Piloting/2 (a 7), +0 for his handling, +1 for a 1 minute turn, +1 for defensive ECM, getting an 16 versus a target of 9. The missile explodes in the distance, doing 6dx5 cr for a total of 97 d-damage against rear hull location 6, the fuel tanks. dDR is 14, so 83 d-damage penetrates, reducing Pathfinder 2 to -3xHP and destroying her engine. Pathfinder 2 makes 3 HT checks against destruction, rolling a 8, an 6, and an 16, and is destroyed. The pilot rolls a 7 on the casualty table, and manages to eject before the Pathfinder goes up, but rolls a 3 on the second casualty check and takes 4 lethal electrical damage which is absorbed by his armor.

Jovian Turn 1: The remaining Jovian pilots are in bad shape: the flight leader has no engine and will be forced to drift uncontrollably from the combat, and the second member of the flight is now helplessly floating in space. Only one member of the flight has survived the CEGA attack with a functioning exo-armor.

Pathfinder 3 is pretty much screwed here. If he doesn't reserve his particle cannon for point defense, another 4 CHS-4 missiles are almost guaranteed to get through and blow him apart. If he launches his own missiles, the superior ACDLS Screen of the Syreens will effortlessly intercept them. Getting a Rendezvous result with any of the Syreeens so he can deploy a plasma lance is highly unlikely. Fleeing the field of combat is the sanest thing to do.

In order to keep the combat interesting, Pathfinder 3 decides to perform 3 tasks this turn: a piloting task for a Closing Maneuver against Syreen 4, a Gunnery Task to perform an Aim and Attack with his plasma lance, and a Gunnery Task to perform to Aim and Wait (Point Defense) with his plasma cannon.

She starts by attempting a Closing maneuver against Syreen 4 and expends 1.8 mps of delta-V at 3G for a +6 acceleration bonus. She then rolls against Pilot-14, +6 for the acceleration bonus, +0 for a Pathfinders's Handling, and -2 for the multitasking penalty, netting a 9 against a 18 (MoS 9). Syreen 4 rolls against Pilot-14, at +2 for last turn's acceleration bonus, -1 for the Syreen's Handling, and -2 for his multitasking penalty, netting a 8 against a 13 (MoS 5). Pathfinder 3 wins by 4, giving the pilot the option of being advantaged or on an attack vector against Syreen 4. She chooses the attack vector, and now both exo-armors are facing each other at Close range.

Close is not Rendezvous range, and Pathfinder 3 cannot deploy her plasma lance. With no better options, she fires both MMJ-4 missiles at Syreen 4. She has Gunner-14, -2 for multi-tasking, +5 for her target's size, +2 for her missile's sAcc, -2 for the Syreen's 2 ECM arrays (halved for the Pathfinder's tactical array), -6 for 10 mps of relative velocity, and +4 for proximity detonation, rolling a 9 vs an effective 15 and achieving hits with both missiles. Syreen 4  opens up with its ACDLS Screen laser as point defense, using all of remaining 600 shots of its Improved VRF laser, and rolls a 12 against Gunner-13, +0 for target size, -0 for sAcc, +0 for Point Blank Range, +9 for RoF and -2 for multitasking (net skill 20) and two interceptions.

CEGA Round 2: At 4 on 1 odds, the Syreens feel good about their chances, and converge on the remaining Pathfinder with intent to laser it to death. Each of them declares a Piloting task to make a Closing maneuver and a Gunnery task to make an Aim and Attack maneuver with the ACDLS. They don't have to hold a task for point defense, since the remaining Pathfinder has launched both of its missiles.

Syreen 1 attempts a Closing maneuver against Pathfinder 3 and expends 0.3 mps of delta-V at 1G. She then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -1 for the multitasking penalty, netting a 14 against a 14 (MoS 0). The Pathfinder rolls against Pilot-14, at +6 acceleration bonus, +0 for the Pathfinder's Handling, and -2 for her multitasking penalty, netting a 16 against an 18 (MoS 2). Syreen 1 loses the contest and ends up neutral and at Short range to Pathfinder 3's front hull.

Syreen 1 then fires her ACDLS at Pathfinder 3. She has Gunner-13, -1 for multi-tasking, +5 for her target's size, +0 for her laser's sAcc, -2 for the Pathfinder's ECM array, -8 for Short range, rolling a 9 vs an effective 7 and missing.

Syreen 2 also attempts a Closing maneuver against Pathfinder 3 and expends 0.3 mps of delta-V at 1G. He then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -1 for the multitasking penalty, netting a 10 against a 14 (MoS 4). The Pathfinder rolls against Pilot-14, at +6 acceleration bonus, +0 for the Pathfinder's Handling, and -2 for her multitasking penalty, netting a 8 against an 18 (MoS 10). Syreen 2 loses the contest and ends up neutral and at Short range to Pathfinder 3's front hull.

Syreen 2 then fires his ACDLS at Pathfinder 3. He has Gunner-13, -1 for multi-tasking, +5 for his target's size, +0 for his laser's sAcc, -2 for the Pathfinder's ECM array, -8 for Short range, rolling a 6 vs an effective 7 and potentially striking. Pathfinder 3 dodges, rolling a 9 versus a base 7, +1 for turn length, and +1 for ECM, and dodges the attack.

Syreen 3 also attempts a Closing maneuver against Pathfinder 3 and expends 0.3 mps of delta-V at 1G. He then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -1 for the multitasking penalty, netting a 11 against a 14 (MoS 3). The Pathfinder rolls against Pilot-14, at +6 acceleration bonus, +0 for the Pathfinder's Handling, and -2 for her multitasking penalty, netting a 8 against an 15 (MoS 5). Syreen 3 loses the contest and ends up neutral and at Short range to Pathfinder 3's front hull.

Syreen 3 then fires his ACDLS at Pathfinder 3. He has Gunner-13, -1 for multi-tasking, +5 for his target's size, +0 for his laser's sAcc, -2 for the Pathfinder's ECM array, -8 for Short range, rolling a 6 vs an effective 7 and potentially hitting. Pathfinder 3 dodges, rolling an 11 versus a base 7, +1 for turn length, and +1 for ECM, and is hit in location 1 of her front hull (an armor location). The laser does 13 burn (2) d-damage against the hardened armor with dDR 21 and fails to penetrate.

Syreen 4 attempts a Closing maneuver against Pathfinder 3 and expends 0.3 mps of delta-V at 1G. She then rolls against Pilot-14, +2 for the acceleration bonus, -1 for a Syreen's Handling, and -1 for the multitasking penalty, netting a 10 against a 14 (MoS 4). The Pathfinder rolls against Pilot-14, at +6 acceleration bonus, +0 for the Pathfinder's Handling, and -2 for her multitasking penalty, netting a 13 against an 18 (MoS 5). Syreen 4 loses the contest and ends up neutral and at Short range to Pathfinder 3's front hull.

Syreen 4 then fires her ACDLS at Pathfinder 3. She has Gunner-13, -1 for multi-tasking, +5 for her target's size, +0 for her laser's sAcc, -2 for the Pathfinder's ECM array, -8 for Short range, rolling a 10 vs an effective 7 and missing.

Jovian Turn 2: The pilot of Pathfinder 3 is elated at her mostly successful dodging of enemy lasers, but recognizes that a huge part of her advantage was burning delta-V like it was going out of style, and that she can only keep that up for another minute or two before she runs dry. With her missiles fired to no effect and lacking a secondary point defense system, she's still going to have a hard closing close enough to use her plasma lance, and using her particle cannon in direct offence means she'll get tagged by 4 CHS-4 missiles and most likely destroyed. She opts to take a Piloting task to Retreat, using her delta-V to rescue Pathfinder Pilot 2 and reroute the heavily damaged remains of Pathfinder 1.

CEGA Turn 3: The CEGA forces are quite happy to watch the Pathfinders depart, and devote their efforts to rendezvousing with the Carolina and recovering the floater.

Conclusion

Well, missiles are probably overpowered in GURPS Spaceships unless they are well matched by point defense. A single 30 KJ VRF Improved Laser turret in each Pathfinder's Medium Battery (which they have space for) would have allowed all of the Pathfinders to survive through the first turn. Indeed, the Syreens would probably have been forced to close up and use their ACDLS and hope for some lucky hits to penetrate to Pathfinder's rear hull armor. With a dedicated point defense system, the Pathfinders could have engaged at range, using their particle beams as offensive weapons.

I didn't put a point defense system on the Pathfinders because they don't have one in JC. Though arguably that's not true, since the original Mekton II version of JC had a bit of fluff that said that all space craft had energy shields to deflect debris. Either way, point defense is clearly a necessity in GURPS Spaceships to deal with missiles, so it's sad that so many of the book designs don't have it.
I've since added the Arclight-3 PDS to the Pathfinders and rearranged the battery location to provide better coverage, so these comments may be slightly nonsensical to people reading now.

The other thing I noticed about these designs is that they were severely limited in delta-V. Another fuel tank for each ship would have been really helpful in increasing their combat endurance. A second engine might have helped with their ability to withstand damage.

For a bunch of other reasons, I really want to redo the JC conversions with some house ruled-systems. I'm leaning toward making the Jovian Chronicle "Plasma Combustion Chamber" (PCCs) into a TL10^ Fusion Reaction Engine with 0.1G acceleration and 75 mps of delta-V. Basically, a Fusion Torch that trades acceleration for delta-V. The lower acceleration means that most JC ships and exo-armors would need to have multiple PCCs, which pleases me.

7 comments:

  1. First of all, let me say the I think you did a great job.
    However, I think you made a small mistake. When missiles are fused for proximity detonation they can achieve multiple hits:
    "If a proximity fused conventional warhead explodes, score one extra hit per full multiple of Recoil by which you make your attack roll, to a maximum of the number of shots that were actually fired (or 10x that if using a proximity-fused conventional warhead). Recoil is 1 for missiles." (SS 1 p 60).
    If I read this correctly, a conventional missile can make up to 10 hits - depending on MoS. So for example, in CEGA turn 1, when syreen 1 gets a MoS of 4 there are actually 4 hits instead of just one.

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    1. If I only made one small mistake, I'm coming out ahead.

      I totally missed that bit about proximity explosions on my first read through, and... wow, that would just be awful. The Jovians would just be annihilated.

      You're absolutely right. Syreen 1 hits Pathfinder 1 with MoS4, gets 5 hits (1 + MoS), Pathfinder 1 soaks 1 hit with point defense, and then 4 missile hits dramatically overkills it.

      Based on some comments by Dave Pulver on the SJ Games forums, I think it would be fair to give to give proximity missiles x10 RoF and 1/5th damage. But then you need to adjust the RoF rules and it gets all complicated again.

      I've got a rework on this combat example queued up for tomorrow (and no use of proximity missiles, yay!) and then I want to do a capital ship engagement later this week. After that, I'll throw out some house rules for adapting Jovian Chronicles to GURPS Spaceships.

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    2. I always felt like the proximity missile rules was "double dipping": you get an effective RoF of 10 (+4 to hit), and every hit does the same damage as the whole missile?
      Logically the damage should be lower since the fragments have less mass then the original missile, so I think reducing damage by a factor of 5 is probably the way to go. In fact if you wanted to reduce the power of missiles in your game you could probably reduce it by even more.

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    3. We should also remember that the weapon damage and armor values in GURPS spaceships are meant to portray "realistic" combat which is similar to modern naval or air warfare, where platforms are lightly armored and weapons are very powerful.
      If you are trying to do a space opera setting these values should probably be changed.

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  2. The name may have thrown you, but I'm the OP on the thread over at the SJG website, so thanks for taking the ball and running with this.

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    1. You're welcome.

      I'm frustrated that the thread has drifted into "are missiles balanced? realistic? wah wah wah?" instead of an actual discussion of the couple of posted example combats. The forums tend to rat-hole too much, sadly.

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    2. I didn't feel much like dragging it back into example territory as there were literally no examples, and only Fred really had any experience to share.

      We're in the home stretch of our packing the house to move cross-country, but once we're there and settled in, I'll likely break out the rules, the hex map, and make an attempt at a few battles myself.

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