Time travel is certainly one of the core of science fiction. It is said that time travel can be achieved through three methods. By travelling faster than the speed of light, black holes and wormholes. The first method, travelling faster than light, is actually impossible if we follow the law of physics. No object can travel at the speed of light besides light itself. However it might be possible to travel close to the speed of light. As an object approaches the speed of light, time slows down. Thus those who travel close to the speed of light might experience few minutes, however those within the normal time flow sees it as hours, or even days.
The second method is actually close to impossible as well. Blackholes are remnants of mega stars that ran out of fuel, ending up being crushed by its own massive gravity. It is said that mass affects the flow of time. The bigger the mass, the slower time flows around it. Blackhole, being the object with the greatest mass in the universe has the power to slow down time considerably. In fact, it is said that time is halfed within the event horizon, the area where escape is no longer possible due to the gravity pull. The idea is to use a spaceship to orbit around the black hole, right at the boundary of the event horizon. However, this could only be achieved way far in the future.
Last method, the wormhole. Wormhole is by far, the most possible method available for human to travel through time. This idea is by travelling through a shortcut between 2 dimension. Time flows differently within wormhole and outside.
Time travel is certainly a dream all physicist wanted to achieve. However, the possibility is very small due to the boundaries of law of physics. Black hole is the only object that ignores law of physics. However, the concept of time travel opens up to many possibility for a game to develop, both sci-fi and fantasy altogether.

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