I have a concept ready and now am working on a quick design document.
The game will be a platformer / metroidvania. As you progress through the game, there will be obstacles and challenges that will hinder the player.
The player then will be able to open portals or rips in the current reality to reveal various parallel dimensions.
The player will collect various items that will allow them to open various dimensions, such as hell worlds, heaven, water worlds, rocky worlds, forest worlds, and worlds that dilate time.
So one idea was the player would come across a river and then open a hell world and bring a lava flow to quench the river.
Another idea was that something is falling fast at the player, and they could open a rip to where time slows down near the rip.
Little bit ambitious at the moment, but will trim down some of the dimensions to make it in the time limit.