Not a videogame per se, but still a potential timesink for some of us. I like it anyway.

Space Engine is a free space simulation software that lets you explore the universe in three dimensions, starting from planet Earth to the most distant galaxies. Areas of the known universe are represented using actual astronomical data, while regions uncharted by human astronomy are generated procedurally. Millions of galaxies, trillions of stars, countless planets!

So, a space simulator. Allows FTL travel to get between universes. No interesting creatures like Noctis had, but it is very pretty sometimes.

Edit: Also prone to crashing. Such is life.