Tactical space combat: A prototype design

My original plans for tactical space combat in Predestination involved making a good attempt at turn-based 3D combat, which is something no game has done well yet. I had intended to make line-of-sight mechanics and area effects a big part of the gameplay, but every combat would have quickly become a chaotic mess. Our main goal with Predestination is to bring proper turn-based strategy back to 4X games, so after discussing the idea with the rest of the team we decided to use a classic 2D combat plane on which tactical decisions are much more obvious.

I started prototyping the combat system last week with a chess board and some coloured squares, but I quickly ended up with pages of complicated rules and movement/attack tables. The Art Director suggested a hexagonal grid and we quickly hashed out a very simple, intuitive system using that grid that we’re all very happy with. We prototyped the system using a big hexagonal gaming mat and paper cutouts and ironed out all of the flaws we could see. The end result is a tactical combat system I’m really excited about:

Movement on a hexagonal grid:

Each ship has a movement speed value based on its size and thrusters. I costs 1 move speed to move into any of the three hexagons in front of the ship, and 1 move speed to turn the ship by 1/6 of a hexagon. These two simple rules combine to produce the movement chart below, which shows the minimum movement speed required by the ship to reach each square. The turning costs make it faster to move forward than sideways or backward. You might be able to get special engine mounts that decrease turning cost or increase speed but make turning more expensive, which would produce very different results.

Attacking on a hexagonal grid:

Each weapon has a range in squares and a firing arc type that determines the area in which it can fire. The default is a standard forward arc the covers the three squares in front of a ship and those in front of it, and doesn’t spread out. Other possible firing arcs include an extended arc that spreads out, a focused arc that only covers squares in a straight line, and a 360 degree arc. You’ll modify weapons to use particular firing arcs by fitting them on a special weapon mount. For example, an artillery weapon mount might double the weapon’s range but reduce its firing arc to a focused line, or a point defense mount could half a weapon’s range but give it an extended firing arc and another bonus. 360 degree arcs would probably have to be restricted to starbases, stationary defense platforms and point blank area effect weapons. Two examples of firing arcs are below:

Reactive Strikes:

One of the main goals for Predestination is to add more strategy to today’s 4X gameplay, so for combat we knew we had to do something more strategic than basic move and fire gameplay. We drew some inspiration from chess to come up a system we’re calling Reactive Strike. When a ship moves into the firing arc of an enemy ship, that enemy gets a free automatic shot at him. Moving out of a ship’s firing arc doesn’t cause a Reactive Strike, but every square you move that ends with you inside someone’s arc will cause one. There’s no limit to the number of times a ship can fire a Reactive Strike, so if you move through four squares that are each in an enemy ship’s firing arc you’ll be fired on four times! These shots are free, they don’t use up a ship’s movement or firing for the turn.

In the image above, two Destroyers with 2-range forward arcs are blocking a Battleship’s movement. If the battleship moves into any of the light red squares, he’ll trigger a reactive strike from either ship. If he moves into the darker red squares, he’ll trigger a reactive strike from both ships as these squares are in both Destroyers’ firing arcs. In real game situation, the battleship would probably opt to stay still but turn and fire on either ship. This could be part of the red player’s strategy, to stop the battleship moving forward for one turn by sacrificing small ships. There’s also nothing stopping a player from doing this with larger and tankier ships.

The goal of this system is to make moving and positioning your ships more than just a matter of getting in range to shoot. Ships can group together to form barriers to enemy movement, areas that if the enemy moves through them he’ll be torn to shreds. You might decide that the chance of being hit and damage dealt on a Reactive Strike is low enough to take the hit, or use longer range guns to outrange the enemy’s firing arcs. There will even be special weapon mounts that increase the damage done by Reactive Strikes, allowing smaller ships to really threaten larger ones. I could also make weapon mounts that increase a weapon’s damage but remove its ability to fire Reactive Strikes.


Inititative system:

A problem that every turn-based game has is that the player who goes first gets a major advantage. I’ve tackled this problem with an initiative order system that merges both sides’ turns into a single action order list. Every ship on both sides of a fight rolls initiative and ships then take turns from highest to lowest initiative score. The initiative order of all ships is known at all times, so you can plan a combat strategy around knowing that certain enemy ships won’t be able to move and fire for a while. The initiative roll is a random amount plus the ship’s initiative bonus, with smaller and faster ships getting a higher bonus.

This means each side will reliably start the fight with its smallest ships, so you can build a strategy around those ships. For example, you could give all of your frigates point defense weapons and set up a perimeter to stop the enemy breaking through to your bigger ships. The battlefield will be big enough that players can’t reasonably get in range to fire on the first turn, so the first turn will be about moving your ships into tactically superior positions to the enemy. You’ll block off areas with your firing arcs, move to the sides to try to get in firing range of an enemy without entering his firing arc, etc.


I’m very excited about this system and hope to start programming an in-engine gameplay prototype soon (as free time allows). I find that the best tactical gameplay usually arises from the interaction between a few simple rules, and I think the system above captures that well. All the rules are simple enough to pick up in a few minutes, and yet in our pen-and-paper prototype play tests we found quite a bit of complex strategy coming out of them. Elements like firing arcs, turn order and valid movements can be easily shown via the user interface, and the Reactive Strike system turns the battlefield into a chess board. If you have any feedback on the system above or suggestions for ways it could be improved, please leave a comment and I’ll definitely take it on board.

14 Responses to Tactical space combat: A prototype design

  1. Pingback: Fleet combat hex system first prototype | Predestination – an indie space 4X game

  2. I think the 2D approach would definitely work better than 3D. I think it would be too confusing with a system like this in 3D and I’m not sure how you’d even represent it on screen. It’s nice to see the turn based combat system. There seems to be TBS games coming out that use RTS combat systems. Like the Reactive strike mechanism and the Initiative system. Really like the “chess” type of battles this will produce and very much like to see how it works out in practice.


  3. Looks promising :). Finally a game which plays combat similary as moo2.
    If you don’t mind I put some of my ideas here (mostly how I’d improve on moo2 combat):
    -some weapon would require warming up, beam weapons for example were doing less damage in the first turns (like 25% in the first, 50% in the second etc.) this would lessen the advantage of shooting first.
    -i’d keep the battles realtively small by limiting fleet size (with command points or something), smaller fleets with amyn options are better than hundreds of ships.
    -maybe the battle should not really be turn based: not talking about real time, but that turns would have no real begining or end, like it was in homm5. I can’t tell the exact mechanism but it was not in turns, but units moved in a set order (according to initiative). if one unit choosed to wait it was just put some points behind in that list. Very high initiative could mean that a ship moves twice before the slower one could move once.
    -not really connected to actual combat, but I’d like to see a philosophy where a lost fight would not be too devastating for the loser. In moo2 multi the game is usually a 1-2 hours build up, a single fight and then the game is usually over. So a mechanism to save damaged ships for later repair would be nice ( an emergency jumpdrive system for example)

    • Those are some great ideas! I’m addressing the first-turn advantage with a ship initiative system that merges both team’s turns. Smaller and faster ships will get initiative bonuses so that they tend to go first, and the gap between two fleets on the battlefield will be large enough that they can’t just move and fire on the first turn.

      I do plan to have both weapons that charge up and weapons with cooldowns, I’ve always liked that idea :). For example:
      – A beam that charges up for 2 turns and then deals massive damage in a huge area. Forces the enemy to move away from that area or take massive damage.
      – Weapon capacitors that let you fire twice or increases range/damage but takes an extra turn to cool down.
      – Missiles that travel to a target location and deal damage in an area. Missile can be destroyed or ships moved out of the blast area before it arrives.

      Limiting the number of ships in a fleet or providing some way to lessen the cost of losing a single battle are both things I’ll be thinking about as the game progresses. Ideally, after being defeated by an enemy fleet, a player should be able to quickly design and build a counter-fleet to defend against it. I’ll post more on the economic side of combat when I have firmer plans in place for it.

  4. just be sure sips don’t become overpowered or some tactics too powerfull.
    in moo2 a ship (in late game) could take out 3+ other ships in the same kind provided it shoots first (that’s why I tought reducing beam weapon daamge for the first turn would be good, so the other team at least can do some daamge too).
    a cheesy tactic for example combining neutron blasters and transporters. A battleship could have enough fire power to shoot down the marines on an entire fleet then fast scouts with nothing else but transporters could capture the enemy fleet before they even moved once.. :)
    or invincible ships exploiting time warp and stasis fields etc :).
    would like to see componets/abilities in your game too, just they need to be made not too “cheesy”

  5. Why don’t you copy the battle system from UFO apocalypse? Set commands to each of your ships using command points leaving a reserve for reactive action once it presents itself. You can add the odd admiral here and there to have a personality in the way each of your fleet reacts.

  6. Hi,
    looks interessting, but is it the only way to get extended for the price of lower range or is it as well possible, like in MOOII, to get it for higher price and more space used but with the same range?

    • and another question. are reactive strikes over the whole range of the weapon or shorter?
      i would suggest to half the range for the reactive mode or you need some additional systems for cost/space to enhance it again.

  7. You should go 3D. Old games 2D and they beat you already (they free, already avaiable, modable, portable)
    Use the map from old space flight sims to go 3D: Avarage distance beatween all visible objects marks a 2d plane, and every object have a squared line drawn from it on the plane to visualise height or depth. (make it dynamic selecting ship moves this plane to it’s hieght to simbolize turrets avaiable shots on bottom of ship or top.)
    Modern turned base games harvest commands from both team in same time, and plays out the turn in motion when both team confirmed end of turn.
    You wan’t more connected play? Allow pause durring this plays out part to activate abilities, rearrange shipt atributes (turn weapon off, overcharge shield), allow to cancel a given order, target changing.
    Pause needs too fast reaction time? Make it only avaiable to preset conditions. Autopause on new enemy sight, autopause when ship enters pre-specified state (no shield, hull under x%, target lost/destroyed) More often then not these conditions will match oposing player’s conditions so he wouldn’t mind.
    Reacitve shot = movement range of units in Heroes of might and magic. Knowing that within a certain distance enemy units will be able to move on you and do the first attack on you puting you in a state where you can only attack with a less unitcount beacuse of that attack. IT IS NOT NEW and NOT GOOD. Player with longer range of weapon autowin, enemy won’t move only in small increments to charge after in hope to lose less before within own fire range etc etc very very bad idea. Kiting oh god no.
    My head really hurts so I stop writing now.

  8. I get the feeling that walls of very long range, focus fire ships (otherwise known as Artillery) will be very dangerous. In small scale combat where there is a lot of flank area you can maneouver around the flank of their formation, but what happens when they cover an entire side of the map?

    I see you winding up with a mexican standoff where nobody wants to risk moving close enough to take a shot. Practically speaking, if there is a 50% chance to lose a ship to reactive fire as you advance into your own firing range, you will lose half your ships before you even get to fire back! Even given that your firing range is the same as theirs.

    You didn’t mention it, but hopefully you are considering some mechanism to avoid such standoffs. The latest X-Com game used a blanket penalty to hit chance with their overwatch mechanic. Another possibility is ship equipment that massively reduces the chance of reactive strikes hitting. Naturally, that would require some fairly stiff cost to prevent it becoming automatic on every ship that can use it. A third possibility is simply relying on AOE weapons as line breakers, but you’d still have to brave heavy losses to get them into action.

    Possibly the best solution is to scale the size of the battlefield to the size of the forces being used, thereby preventing either side from creating a “wall of fire”.

    Good luck with the game!

  9. This looks really cool. Have you ever played Flotilla? That does full-3D strategic turn-based combat really well.

  10. I love the concepts behind this game. Its about time time some one i stepping up and adding even more to the beloved space 4x genre. Though the thing that would really make my day is having a movement and battle system similar to the table top game Babylon 5 wars. Any one still play this? It uses real space physics as far as movement is concerned. Each ship has a power limit and thrust limit depending on its movement and acceleration. We all know from Newtons laws that an object in space will have content volatility unless altered. weapon fire should happen simultaneously I think to still have the turn based feel and yet have events happen at the same time like it would…

    Well that’s my two cents hope someone is listing

    • Oh and ship systems…I mean come on now huge ships run off of systems and if one is to be destroyed it can mean the difference in a tactical battle