Peeling open a fresh pack of Pokemon cards, full of excitement about what rare cards might be mixed within. The nostalgic feeling from childhood is back, but this time in the form of a new mobile game, which has taken the world by storm within the first two weeks of its release.

Since Pokemon Trading Card Game Pocket — or "Poke Poke" for short — was released on Oct. 30, the novel yet nostalgic game app had amassed over 30 million downloads worldwide as of Monday, having consistently remained on top of the download charts in the Japanese iOS and Android app stores.

In the past two weeks, developer DeNA has raked in over $50 million for the app — which is free to download and play but charges for premium features — according to AppMagic, a mobile app market research website. This is not surprising, considering that the company's share price surged when it announced the game earlier this year.