NiBiRu is a fantasy adventure game. In this game, the player assumes the role of Martin Holan, a student of archaeology and linguistics. Martin is summoned by his uncle, a university professor, to make his way to Bohemia and investigate a recent discovery. While building a new highway, workers discovered a World War II-era tunnel. During his exploration, Martin uncovers mysteries and puzzles that must be solved. Players must pay close attention to what they find in the tunnel, as well as take note of the conversations they have with other characters.
What starts as a simple tunnel exploration turns into something more complex as Martin finds out that the woman his uncle sent to meet him has been murdered. Along with the tunnel being a Nazi hideout, Martin also discovers that the tunnel is somehow linked to the Mayan civilization.
The game interface is simple and easy to navigate. Players can move the cursor to the cogwheel icon at the top right of the screen to access the main menu. NiBiRu enables players to save their games; players can save up to 100 games. Players can also overwrite a saved game. At the bottom of the screen is the inventory bar where players can see the items they have collected throughout the game. Players can combine items by selecting one and clicking it over another item. The items are used to solve the puzzles.