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Achron and the Grandfather Paradox

When it comes to paradoxes, some people initially say 'my head hurts'. We remind them that paradoxes are rare and are resolved by the game for the player. The player doesn't have to focus as much on the paradoxes and can concentrate on their overall strategy.

Time travel is a familiar concept, but because people aren't used to thinking in terms of time travel, they often jump to the most complex scenarios and paradoxes. However, these complex scenarios are not typical in gameplay unless you purposefully cause them. Usually you're just modifying a history you are familiar with because you just played through it.

Q: How the game would resolve the following complex example: Player A sends units back in time and destroys player B's factories. Before the timewaves reach the present, player B sends his army back in time and destroys player A's factories?

A: This is definitely a paradox. It will oscillate between these two states. If you're a very accurate player, you might be able to time everything such that the paradox falls off the timeline in your favor. Paradoxes aren't very common in games unless you cause them yourself, so they tend to happen more frequently in games between advanced players (if we crank up the AI difficulty to 11, this does happen frequently).

A Wikipedia Definition of The Grandfather Paradox


Full Transcript:

This is a demonstration of how Achron's game engine, Resequence, handles the Grandfather paradox. For this video, we have specifically tuned time waves and build times to make the Grandfather paradox easy to show quickly. Remember that paradoxes like this are rare in actual gameplay unless you cause them intentionally. In this demo you will see the oscillations of both outcomes of the paradox on the timeline and on the field.

We begin by creating a mech with the factory - note the green on the timeline shows when the mech was created. We now send this mech to before it was created - The yellow on the timeline denotes chronoporting. We create the paradox by destroying the factory with the mech - The red on the timeline shows the destruction of the factory.

As you look at the timeline, you see that each subsequent timewave grabs the previous change and propagates it forward. Now that the factory is destroyed in the past, the mech can no longer be created. Since the mech was no longer created, it could not travel back in time to destroy the factory, so the factory can again build the mech. You can see this oscillation repeating on the timeline as it gets closer and closer to falling off. Looking at the field, you will notice that these subsequent time waves keep changing the outcome, alternating between the two paradox states, with either the factory surviving or the mech surviving.

If the mech-jumping-into-the-past is the last thing to be propagated by a time wave, then the factory will survive because the mech will have jumped beyond the edge of the timeline. In this example, you see that the factory survived.

We will now repeat this paradox again with different timing such that the mech will survive instead. Note that this is a very advanced tactic, and that attempting this in actual gameplay with complex paradoxes is risky because your opponents can potentially disrupt the timing. As these oscillating events fall off the timeline, if the destruction-of-the-factory is the last event to be propagated by a timewave, then the mech will survive and the factory will not. All paradoxes in Achron are resolved via this oscillation mechanism that locks them into a steady state as they reach the edge of the timeline.

As you see, the result of this instance of the grandfather paradox was resolved with the mech surviving and the factory being destroyed.


If you watch the video a few times, you may come up with one of these questions:

Q: I've been thinking about the grandfather paradox and similar paradoxes non-stop for the past week. What if you cause a grandfather paradox, and just before the unit-jumping-back-in-time falls off the timeline, you prevent it from jumping back? Because the unit's arrival in the past is off the timeline, you have just permanently chrono-cloned the unit, right? Because of this, won't all games end up being cloning armies like this?

A: You really have been thinking about this a lot. Yes, you can permanently chrono-clone a unit this way to end up with two of the same unit. However, to do so you will:

Q: In the video, when the paradox resolves to the mech destroying the factory, the factory never built the mech. Does that mean you've gotten the mech free of cost (got your resources back) in exchange for your factory?

A: Yes, however, we've taken careful steps to make sure that this "free" unit is not actually free:

It comes down to the choice between a small gain in resources at the cost of 1) a more complex and difficult timeline to manage, 2) a lot of chronoenergy spent managing the complex timeline that may be better spent preempting and reacting to your opponent, and 3) having periods of being weaker and easy prey to a clever opponent.

News & Game Updates

Release v1.6.5.0

Mon, Oct 13, 2014

Summary: This release contains numerous bug fixes and adds new modding capabilities to Resequence.

If you have already ordered Achron, you can download it here.
» Read More & see the Changelog

Release v1.6.4.0

Tue, Sept 1, 2014

Summary: This release contains numerous performance improvements, especially for rendering and multiplayer, as well as numerous bug fixes.

If you have already ordered Achron, you can download it here.
» Read More & see the Changelog


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