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Terajoule is an (ostensibly) easy-to-play wargame about realistic space combat. It's currently still being worked on for balance and playability.

Terajoule was first introduced to elegan/tg/entlemen at large in a thread titled "Semi-Realistic Space Combat," which was about half spaceship dump, half rules discussion and suggestions. The link to the archive is at the bottom of the page.

The rules are below.



At some indeterminate time in the future, people fight in space.

Turn CycleEdit

Each turn consists of the following phases, in this order:

I. Movement

1)Move Ships by mass, resolving ties simultaneously

2)Move Torpedoes in order of mass, resolving ties simultaneously

3)Move Missiles in order of mass, resolving ties simultaneously

II. Firing





5)Point Defense

6)Terminal Guidance

IIb. Damage

1)Resolving Damage

III. Energy

1)Radiate Heat

2)Generate Energy

Detailed Phase WalkthroughEdit


Before the game begins, decide on the rules for the scenario. This will probably include starting vectors for any ships, too.


The game takes place on a hexgrid, with a number to denote altitude. A hex represents a fairly large area of space, so there is no limit to the number of objects that may occupy it at the same time.

Every object on the field has a vector (marked on a separate sheet, probably) indicating their velocity and direction. Each turn, they move that many hexes in the direction indicated. Altitude is also noted on the velocity.

Any turn in which an object accelerates, they may first add or subtract up to their max acceleration from their vector before moving that turn. Use the hexgrid thingy to figure out the new vector. Altitude vector always just adds or subtracts directly; we'll keep it easy and ignore Pythagoras for now. Any turn in which an object accelerates, it marks off 1 Fuel.

Terajoule uses phased simultaneous movement. In general, vessels are moved in order of mass, with the largest moved first and the lightest last. In some cases, there may be ties. When this happens, you secretly mark your change in vector, then reveal it (simultaneously with your opponent) and move that object. In the first phase, all ships move. Second phase, all torpedoes. Third phase, all missiles and munitions.


During this step, objects fire their weapons and activate their various systems. Actions within each phase are considered simultaneous. Any damage inflicted is calculated immediately, meaning, for example, that a shot from a laser might destroy a missile before it can detonate its payload.

1)Launches - Missiles, nukes, and torpedoes may be launched in this phase, either using a railgun or simply being released from the firing ship. They are immediately placed on the same hex as the firing ship, and begin moving next turn.

2)ECM - ECM may be used against missiles in this phase. Any missiles effected are immediately eliminated. Roll 1d6 for each point of ECM targeted at a given missile; any 6s remove the missile. Remember, dice are allocated before being rolled, with 'wasted' dice lost.

3)Lasers - Lasers are fired in this phase. Each laser may fire once, provided the firing ship has enough energy available in its capacitors. Lasers deal hits based on their range and strength, as described below.

4)Detonation - Any nukes, whether attached to torpedoes, missiles, or simply 'dumb-fired', may be detonated. Nukes may even be detonated while still aboard a ship (this, obviously, destroys the ship, but also anything around it). Note that objects within the range of nukes are destroyed instantly, and those one hex outside its range take d6 hits.

5)Point Defense - Point Defense may be used against missiles in this phase. Any missiles effected are immediately eliminated. Roll 1d6 for each point of PD targeted at a given missile; any 6s remove the missile. Remember, dice are allocated before being rolled, with 'wasted' dice lost.

6)Terminal Guidance - Any objects in the same hex as an enemy (of any type) of lower mass, or that could have logically passed through that hex in the last movement phase (use some string) may use this phase to crash into their opponent. This maneuver immediately deals hits equal to the mass of the ramming object times their differences in vectors to both the ramming and the rammed object.

IIb. Damage

Whenever a hit is dealt to a target, break from the current spot in the order and resolve damage as follows: 1)Resolve Damage - Any object which has taken a hit (the arbitrary unit of damage, here) during the firing step then rolls to see the effects of this damage. For each hit, mark off 1d6 squares of mass at random. Any system which loses a square is disabled. If the ship mounts armor, it /must/ use this armor to save first.

III. Energy

Last, we take care of our energy-management for the turn.

1)Radiate Heat - In this phase, every ship may radiate as much heat from its heat sinks as it is allowed. If for whatever reason the ship still has more heat than its heat sinks can hold, it suffers one additional hit per point over the limit. These hits are resolved immediately, as per the rules above. Excess heat is NOT removed - it carries over from turn to turn.

2)Generate Energy - As the last step in the phase, each ship's power supply generates its rating in power. This energy is transferred into its capacitors, up to its full capacity. Excess energy is lost.


Ships are the largest combatants, and often serve as the focus of an entire mission. They may or may not be manned, I don't really care. Ships are provided in the appendix, or they can be designed by the players (the latter is more fun). Your frame determines the basic characteristics of the ship, while all the extra systems are more or less customizable on-the-fly.

Each ship frame has the following components:

Mass - total mass, including systems. Shows the amount of 'extra' customization space you have

Engine - provides Acceleration, but uses fuel and energy, and produces heat

Fuel - how many turns of reaction mass (kinda like fuel) you have

Heat Sinks - how much heat you can store

Radiators - how much heat you radiate each turn

Power Supply - how much power you make each turn

Capacitors - how much power you can store

For starters, here's a pair of basic frames to get started on:

Destroyer (<=100 mass)
 Engine(10 mass) - Acc. 3, req. 1 Fuel + 4 Energy, Generates 1 Heat
 Power Supply(4 mass) - 4 power per turn
 Capacitors(4 mass) - store 4 energy
 Radiators(1 mass) - radiate 1 heat per turn
 Heat Sinks(1 mass) - store up to 1 heat
 Fuel(20 mass) - 20 Fuel
 Payload(<=60 mass) - Contains whatever is desired
Frigate (<=100 mass)
 Engine(15 mass) - Acc. 4, req. 1 Fuel + 5 Energy, Generates 1 Heat
 Power Supply(5 mass) - 5 energy per turn
 Capacitors(5 mass) - store 5 energy
 Radiators(1 mass) - radiate 1 heat per turn
 Heat Sinks(2 mass) - store up to 1 heat
 Fuel(30 mass) - 30 Fuel
 Payload(<=42 mass) - Contains whatever is desired

These two frames are used in the sample scenario (see Appendix).

And any number of customizable extra systems: Lasers Point-Defense Railguns Missiles Torpedoes Armor ECM Packages Extra Capacitors Auxiliary Power Generator Heat Sinks Extendable Radiators Fuel Tanks Mission Pods

Each extra system adds to your ship's mass, and provides some sort of functionality. See below:

Lasers - A common weapon, lasers are multipurpose short-range weapons. Each point of laser takes up 4 mass, and requires 3 power and generates 2 heat when fired. The laser has a range of twice its point total in hexes. Any target in its last hex of range suffers a hit; any closer target suffers 1 additional hit per hex inside max range.

Point Defense - Point Defense protect against missiles in the final stage of their attack. Point Defense takes up 1 mass per point. Each turn, you may roll up to d6 per point of Point Defense against a specific missile in the mounting ship's hex. If a 4 or higher is rolled, that missile takes a hit. Each point of Point Defense may only be used once per turn. Alternatively, point defense can be used to deliver 1 hit of damage per point to targets in the same hex.

Railguns - Railguns are used to accelerate missiles, torpedos, and nukes toward a target. Each point of railgun takes up 3 mass, and requires 2 power and generates 1 heat when fired. When fired, the railgun launches a missile or nuke with a vector equal to the firing ship's current vector plus up to 10 in any direction. Railguns can launch up to their points value in mass this way.

Missiles - Missiles are the smallest class of object, and act as miniature vessels that home in on enemy ships with lethal effect. Missiles come in all types: see the section on missiles for more details.

Nukes - Typically nuclear warheads. Carried in missiles or launched using railguns. One point of nuke has 1 mass. Nukes can be detonated in the firing phase. When detonated, each nuke deals 600 damage per point in the hex it goes off in, with the damage received being divided by 10 for every hex from the epicenter, rounding down.

Torpedoes - Torpedoes are the medium class of object, and differ from missiles in that they use the same style engines as larger ships (and tend to be larger as a result). Torpedoes as a category also cover ECM probes, AKVs, and so on - see the section on torpedoes for more details.

Armor - Armor is used to deflect or absorb hits, though it is quickly compromised. Every time a ship or torpedo with armor would suffer a hit, roll d6s equal to the number of points of armor it has. If any come up a 6, all the damage the hit would have otherwise dealt to vital systems instead effects the armor. Any overflow is distributed as normal.

ECM Packages - ECM prevents missiles from homing in on you. ECM takes up 1 mass per point. Each turn, you may roll up to d6 per point of ECM against any missile on the field. If a 6 is rolled, that missile is eliminated. Each point of ECM may only be used once per turn.

Extra Capacitors - Extra Capacitors increase your ship's ability to store energy. Each point of extra capacitors has a mass of 1, and stores 1 additional energy.

Auxiliary Power Generator - Auxiliary power generators let you generate more power each turn. Each point of auxiliary power has a mass of 1 and generates 1 additional power each turn.

Heat Sinks - heat sinks let you store more heat internally. Each point of heat sinks has a mass of 1 and stores 1 additional heat.

Extendable Radiators - Radiators let you radiate more heat each turn. Each point of radiators has a mass of 2 and radiates 1 additional heat per turn.

Fuel Tanks - Fuel tanks store extra remass (which isn't technically fuel, but whatever man). Each point of fuel tanks stores an additional 1 remass and has a mass of 1.

Antimatter - Antimatter acts as a booster for power supplies and engines, and can make for an extremely powerful warhead. Each 5% that the fuel/antimatter ratio for the ship, missile, or torpedo in question gets closer to 50,50 each point of mass worth of power supply outputs 1 additional energy per turn and the thrust of the craft's engines is increased by 20% with fuel consumption being reduced

Mission Pods - Mission pods don't do anything; they can represent supplies being transported, expeditionary forces, diplomats, satellites, orbital bombardment nukes, whatever. In missions where the objective isn't just 'destroy the other guy', your success depends on getting the mission pods through the fight safely. Scenario Rules (which will vary from mission to mission) will fill in the details.

These next 2 systems are best used for 'campaign' type games, but aren't all

Torpedoes & MissilesEdit

'Torpedoes' is the general term used to describe all smaller disposable-type vehicles that might detach from the main ship and perform some specific mission. It might be to carry a warhead into the enemy ship like a traditional torpedo, or it could house a point-defense array or ECM suites, or perform laser-picket duties. The term 'torpedo' is used to distinguish it from missiles. The main difference between these two objects is their drive system. Torpedoes use the same general drives as larger ships do, which are designed for slow, sustained acceleration at economical fuel rates. Missiles, on the other hand, are designed for short, fast bursts of acceleration at the expense of fuel economy. This makes missiles dangerous but short-duration weapons, while torpedoes are a more persistent threat. A missile that misses has probably run out of fuel and sails off into space; a torpedo that misses turns around for another pass.

Torpedoes and missiles are both designed in the same style as ships, with the exception that they use different base frames and act on a different phase during movement. In addition, torpedoes get 5 remass per fuel tank as opposed to 1. A basic torpedo frame consists of:

Mk.I (<=5 mass)
 Engine(1 mass) - Acc. 4, req. 1 fuel
 Fuel(1 mass) - 5 Fuel
 Warhead(<=3 mass) - Contains whatever you want
Mk.II (<=10 mass)
 Engine(2 mass) - Acc. 4, req. 1 fuel
 Fuel(1 mass) - 5 Fuel
 Warhead(<=7 mass) - Contains whatever you want
Mk.III (<=20 mass)
 Engine(4 mass) - Acc. 4, req. 2 fuel
 Fuel(2 mass) - 10 Fuel
 Warhead(<=14 mass) - Contains whatever you want

The maximum size for a torpedo is 20 mass; past that it's essentially a ship. Note that engine mass is about 1 per 5, but fuel doesn't scale proportionally. That's rough, and kind of a side effect of ignoring F=ma when it comes to acceleration. Maybe I'll rework that later on.

A missile is so simple it almost doesn't need a frame. Here's all you have to work with:

Missile (>=1 mass)
 Engine(0 mass) - Acc. 8, req. 1 fuel
 Fuel(1 mass) - 1 fuel
 Warhead(<=0) - Contains whatever desired1

So in theory, you could have a missile that totals 1 mass. What's the point of such a small small weapon? Remember the rules for Terminal Guidance attacks.

During the movement portion of the game, torpedoes act much like ships, albeit on their respective phases. During firing, torpedoes and missiles act the same way as ships. Note that, in the absence of being launched from a railgun or similar, missiles and torpedoes launched from a ship begin the next turn with the same vector as the ship that launched them. Most commonly, missiles/torpedoes will use either the Detonation phase (to explode nukes in their warhead) or the terminal guidance phase to crash directly into an opposing target. In the latter case, remember that terminal guidance can only be used against a target of higher mass.

For purposes of 'campaign' games and the like, assume all missiles fired are lost. All torpedoes fired can be recovered, provided they have enough fuel to accelerate onto the same vector as their mother ship at the end of the game.

Optional RulesEdit

These are some leftover ideas that haven't been fully developed, but that some people might want to play with. No idea what effect they'd have on balance or gameplay. Use at your own discretion.

Nuclear Shaped Laser Dwell Laser Precision

Compartmentalization - By default, systems are compartmentalized, such that a single hit to a heat sink, for instance, will not destroy ALL the heat sinks, but simply that individual bank of sinks. Depending on how lethal you want damage to be, you can add a few different rules here. For a more lethal game, establish a 'minimum bank size' - the smallest number of squares that can be compartmentalized. My default rules assume this size is 1 (a point of damage to a capacitor only takes 1 point of capacitors offline), basically assuming that compartmentalization is fairly easy. Setting minimum size at 5 (a point of damage to capacitors etc. would take 5 points worth offline) quickly increases how quickly ships fall apart.

Catastrophic Failures - By default, a system taking damage just means it can't be used anymore. You could decide that certain systems are prone to catastrophic failures: if they suffer a point of damage, they might inflict some additional consequence. (as an example, a damaged power supply might explode violently)

Undermass Railgun Loads - Increasing the power of a Railgun simply means that it's able to impart more energy to a projectile. This could be used to either fire a larger projectile at the same velocity or fire the same projectile at a much higher velocity. For every additional projectile of that mass the Railgun could theoretically launch during that turn, the velocity change delivered to the projectile may be increased by 10.

Close range kinetics - When a kinetic weapon is shot at utterly ludicrous speeds, this tends to make it a less effective weapon as you can't get the hexes the two objects are in to connect, and if you're using a string you simply can't change the launch angle fast enough. In real life, that ship simply wouldn't have had TIME to get out of the way, and the kinetic would have hit. When this rule is in play, if the projectile (via string) traveled through the hex the target would have been in had they not accelerated, and the distance between the projectile's starting point and the target been 20% or less of the distance the projectile traveled during that turn, the projectile may make a terminal guidance attack. (Note: this rule isn't perfectly scientifically accurate, but it's good enough for gameplay purposes)

Relativistic weapons - Any missile or torpedo moving at 25,000 hexes a round or more relative to its target counts as relativistic. A relativistic projectile is completely immune to ECM or point defense for the simple reason that in universe by the time the target realizes they're about to die, the shot has already hit.

Ablative armor - If you're tired of nukes being 1 hit kills, then make each point of mass a nuke has simply add 15 hits at hex zero, with each hex of distance from the center of the blast making the damage recieved 15 hits less powerful. (They're still powerful, just not 'vaporise the entire death star instantly' powerful.)

Gameplay QuestionsEdit

Q:Lasers hit anything in a hex they pass through* - does this destroy missiles in the firing hex? Q:Citation needed - DO lasers hit anything they pass through, or is it only the target at the end? And do lasers also hit friendly targets? A:Lasers only deal hits to their targeted hex, and only to intended targets. My assumption in this regard is that hexes are much (MUCH) larger than the width of the laser beam, and that the laser beam can be aimed fairly accurately, so it is unlikely to hit anything it didn't intend to. Space is large, and light is precise. The actual rule should be that the hits dealt by the laser are divided among any number of targets in the last hex - targeting a hex with 50 missiles in it doesn't allow you to deal 50 times as much damage. Likewise, lasers can be used against missiles in the firing hex - laser damage is intentionally dealt before terminal guidance damage so that lasers can be used as "point defense on steroids" if needed.

Q:If two missiles inflict hits on a ship with Armor and the Armor rolls three sixes, does it lose two points of armor or three? A:The intended rule is that all damage is dealt separately, so there's no such thing as "two missiles" inflicting hits - just one missile inflicting a hit, followed by another missile inflicting a hit. Armor would be rolled for each missile separately as well. Somebody (wisely?) reworded the Armor section such that only 1 six is needed, and all damage inflicted is allocated to armor. My original rule would have had those 6s wasted - this was intentional, as I don't think armor in space will be particularly effective. That might be more a matter of taste than of science, though.

Q:If a laser hits something in the first hex, does it deal less damage to the hexes beyond the first due to chaff? This could make defensive missiles very useful even at short range against a Hoplite-class ship. A:See above - lasers don't hit things in more than one hex. What is this idea of defensive missiles, though? Sounds interesting.

Q:How do you 'randomly pick' a mass unit to write off when damage is inflicted? Do you roll 1d100 against the table, with one digit being columns and the other rows? That's a lot of work, but rolling by system is hardly fair as it gives an equal chance of hitting your 30 units of fuel and your nuke. A:My intention was the former: d% by row/column, or some other purely-random arrangement.

Q:When fired, a railgun can launch up to its rating in mass. Does this mean a rating-4 railgun can launch four mass-1 missiles per turn? Can they be on separate headings? If it can fire several missiles at once, does that mean it gains heat for each missile? A:RAW, I'd have to say no, because it specifies "_a_ missile, torpedo, or nuke." My mental image was that four small railguns are not equivalent to a single large railgun. However, maybe clever engineering can make this work as you would intend? I can at least kind of imagine set-ups that would allow multiple launches, so it seems silly to rule that they wouldn't work. If you decide to go with this, the railgun does not gain heat from each missile - it gains it when fired, and the single firing launches all 4 (or however many) missiles at once.

See AlsoEdit

External LinksEdit