Causality : A time-reversal game

The Game

Causality is a reflexion and puzzle-based game that plays with temporality and the flow of time.

The game will be made up of a lot of small levels that can be view as individual puzzles following a main story and quest. You will have to finish the different levels two times: the first time is like any other game where you need to reach the end of the level, and the second time you’ll have to do the opposite, as the time is going in reverse…

The Character

You will be playing as Livy, a blue-haired girl with an ability to control the flow of time. Livy has no fear and will not hesitate to brave the biggest dangers and manipulate the flow of time to accomplish her mission.

The flow of time

As soon as you finish the level for the first time, the time flow will go in the opposite direction, meaning that the time itself will go backwards. Everything that happened since the beggining of the level will happen again, but in reverse order; this includes you character and its movement along with the elements, obstacles, animations and enemies present in the level.

You can see this behavior when you finish a level, every move and jump you’ve just done is repeated (and you’re not in control of the movements of this character anymore as it has already happened):

When you enter the Time Inverter at the end of the level, you’ll still be able to control your character (which now has red hair to represent the fact that it’s living in a time that is going in reverse), but you won’t be able to modify what already happened to your past character.

Your new goal is now the opposite : you need to get “back” to the beggining of the level while the time is going reverse. But be careful not to break the causality of events ! You shouldn’t in any way touch your past self or change any element in the level that would result in a causality paradox.

This is relatively easy in the simple level above, but it will become more challenging thereafter.

Self-cooperation

The core mechanic used in the levels is the idea that you will have to interact with your past or future self in different ways, while making sure not to break the causality.

There are two different types of self-interaction :

Helping your future self

The easiest self-cooperation mechanics happens during the first run. This is because in the first run, you don’t have to take into account causality and past actions as they have not already happened.

For instance, in this level you’ll need to create a platform while the time is going forward so your future self can finish the level :

In this footage, you can see that you need your past self to execute a specific action (here standing on the button) so that your future self is able to go back to the beggining.

When you finish the level with your future self, the time will go back to normal and you’ll be able to see the full interaction between your character’s past and future self from the beggining to the end of the level. This final run is only for visualization purpose as you can’t control anything, and this time it’s your future self that is going in reverse through time.

Helping your past self

This kind of cooperation is a bit more tricky as you need to be careful not to break the causality of the level (meaning doing an action that would prevent your past self from finishing the level, thus creating a paradox: if you never finished the level you’ve never inverted the time and so on…)

But how can you help your past self if you are not able to modify the actions that already have happened ? The answer is by using the principle of causality at our advantage. For instance while the time is going forward if you’re walking on a platform that only exists when someone activates a button, it means that the button will be activated in the future by yourself, otherwise you couldn’t step on it.

This also means that in the future if you don’t activate that button, then your past self should not have been able to walk on the platform as it was inexistant and this would create the same causality paradox as before :

You can recognize the platforms that “only exists in the past if they have been activated in the future” by the fact that they never completely disappear and are a bit transparent: it means that they exists if you step on them, otherwise they don’t. Whenever you’re walking on this kind of platform, you should remember that it has to be activated in the future at the exact moment you’re stepping on it :

Manual time control

In addition to the default behavior of time (which starts going backwards as soon as you enter the Time Inverter), you also have the ability to manually control time. At any time, you can start to rewind the time, but be careful not to confuse yourself ! This is not the same thing as entering the Time Inverter.

When you enter the Time Inverter, it will reverse the flow of time for the level and your past self, but you’ll still be in control of your future self, and you’ll have to interact with your past self to finish the level (and avoid causality paradoxes).

But when you enter the Rewind mode, it’s like rewinding on a TV, you won’t be able to control your actions, it will just play them back and you’ll be able to start them over when exiting the Rewind mode.

This has an interesting effect : when you’re rewinding time with your past self, it will make the flow of time go backward as the time was already going forward. But when you’re rewinding the run while the time is already going backward (after passing through the Time Inverter), then the time will appear to go forward while in reality you’re going back in time (relative to you and not to the level) :

Demo level :

Below is the footage of a medium-difficulty level being solved from beggining to end :