I had the big idea of trying to create a hard science fiction 4X strategy game (with the obvious space setting), which is supposed to simulate a realistic way of creating interstellar societies while simulating real life physics as well.

The problem is: how do I apply Einstein's relativistic equations into the game? I will make a separate series of questions for other issues, such as applying Keplerian planetary movement and Newtonian combat physics.

Do note: the game is being made in C++ and in Unity. Be warned: I am trying to simulate special relativity, not general relativity quite yet. That I can try in a different game.

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    \$\begingroup\$ As a game designer with a master's degree in physics (argument from authority fallacy), I will say that realistic physics seldom results in fun gameplay. :) \$\endgroup\$
    – Almo
    Dec 2, 2015 at 16:00
  • \$\begingroup\$ How does it not end with fun gameplay? I want to take into account 3 things: Keplerian movement in my game, relativistic physics taking into account LONG communications delays, and slow year-spanning travel since FTL technology in-game is non-existent, and Newtonian combat. Basically, showing how space battles would work in real life. So, my problem is: how would handwaving all that in the game make it feel new and fresh? \$\endgroup\$ Dec 2, 2015 at 16:09
  • \$\begingroup\$ It's something I've learned from building and playing games over the last 40 years. Take Rocket League for example. This is a very popular and very fun physics-based game. But if you play it for a just a little while, you'll see the physics (at least the constants used, like gravity and restitution) aren't realistic. It was tuned to be fun. I'll just take one example... I fail to see how long communication delays will be a fun mechanic to have to deal with. boardgamegeek.com/boardgame/4815/campaign-north-africa Read a bit about this board game to see how realism panned out for it. \$\endgroup\$
    – Almo
    Dec 2, 2015 at 16:16
  • \$\begingroup\$ So to make it summarised: realistic physics would make the game more tedious to play, or at least end up with some results that would not be the most beneficial to the game. Is that correct? \$\endgroup\$ Dec 2, 2015 at 16:24
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    \$\begingroup\$ Agreed. Even if you have a solid argument for why special relativity would be interesting to experience in a 4X, it's very unlikely that all of its consequences happen to align with what people want to experience. I think you could start with simple(?) prototypes of the various consequences of SR and see if something fun jumps out at you. Have others playtest them too. If several people enjoy something, that effect may be worth taking into a full game. Even then you must be guided by the integrity and fun of the experience, not faithfulness to the feature. \$\endgroup\$ Dec 2, 2015 at 16:42

3 Answers 3


Ultimately including special relativity will put limitations on the players ability to control and monitor their empire.

The most important aspect I think would be as you mentioned, communications delay. This could be implemented in different ways,

  • omnipotent player - this player is not limited by relativity and is aware of everything that occurs in the galaxy (can include normal fog of war etc). The limitations occur when sending orders to systems/fleets far from the empires homeworld as orders take time to arrive.
  • limited player - this player is limited by relativity and so sees a previous game state depending on how far away that part of the game is. This means that knowledge of what might happen becomes much more important. (I can imagine this would be quite annoying)

Either of these could be frustrating but I think if you give the player ways to combat these limitations they could prove to be interesting mechanics.

Some ways to do this could be,

  • allow the player to prepare distant systems for different situations i.e. if an enemy is detected approaching one system others back them up.
  • give the player several 'heroes' through whose eyes they can observe the universe around them and so see up to date information. The relativistic effect would be similar to a fog of war around these heroes and cause them to observe those distant systems in a previous state.

Note: sorry if this is not what you are looking for but instead want help with actual implementation. I would welcome any help with editing etc as I tend to ramble. (I would have commented but unfortunately don't have high enough reputation.)


To help with potential implementations, I think a good first step is OpenRelativity.

You can also explore the game they made - A Slower Speed of Light - to see whether different SR consequences are interesting to you.

On the page for ASSOL you can also find links to some related publications about the experience and intuition around relativity in a game, which may guide your thoughts on how to apply them to a 4X.


I am no game designer or have any qualification but I have an idea for a realistic tactical semi turn based ship to ship combat system.

Ideally it would be full 3d movement but it is likely easier to explain in 2d.

So you would have the area of space between the 2 ships. This is measured in light seconds. Therefore at the start lets say there is a 120 light seconds between you and the opponent. You therefore have the position of them 2 minutes ago.

You then plot a course for your ship. in practical terms this would be taking your ship and placing it in the place you want it. The computer would then plot the course and tell you at what time point you would arrive at that point. a line would be drawn from your current location to the end point. The plot could be adjusted by dragging the line.

At the bottom of the interface would be a slider that you can use to show where various objects, such as the enemy ship, will be at a particular time (assuming there is no changes).

Once you're happy with the plot you can hit play and the ship will follow the commands. Now as ship to ship combat in space is actually likely to take weeks (and no one wants to play that) there will be a fast forward button. If you hit fast forward the game plays out until you pause it or there is a change in direction in the enemy ship.

remembering of course that the change is course will be reported late as you have to wait for the light to reach your ship. So you know say 120 seconds ago the ship changed course you can then project its current position (assuming no further changes of course) using the time slider and you position assuming no changes of course. You can then adjust you course in response to thier adjustment. And so the game plays out.

Combat therefore becomes more about placement of the ships. It also become faster as the ships get closer. The skill will be in placement, angle of attack and speed.

If the ship engage at high speed you could add in an effect that causes the weapons to miss due to time dilation.

Add in power and fuel constraints and need to flip 180 to burn main engines to slow down.

You get an RTS style game play with realistic physic deep and complex game play.

This Could also be expanded to fleet combat creating tactical decisions on whether to attack on mass or split and when to split etc.

At the moment the only tactics in space combat is how large is your fleet and how quick can you get it into the fight. Also if you wanted a low graphics solution do it as a tactical plot rather than a realistic representation.

I hope this makes some sort of sense. I came across this post whilst trying to find a game that did something like this.


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