The Unforgettable Occasion

After a group of adventurers spotted a small cube, mysterious creatures began appearing and humans suddenly obtained powers. Humans have began to grow stronger and promises to eliminate every creatures. Though the creatures also have began growing. Not stronger but smarter. Humans have then discovered that there are different worlds either similar or differently from theirs. No one knows how to travel nor knows what it's like on the other world, but a certain someone will definitely travel the world.