Final answer:
The 1986 video game where Luigi and his sibling rescue Princess Toadstool is titled Super Mario Bros.
Step-by-step explanation:
The title of the 1986 video game where Luigi and his sibling try to rescue Princess Toadstool is Super Mario Bros. This classic game is an iconic platformer developed by Nintendo where players navigate through levels to save the kidnapped princess from the villain Bowser. It's a two-dimensional side-scrolling game which introduced many to the video game world and is considered an important piece of video game history.