Introduction
Explore mode is the main attraction of Run 3. Run 3 is the only game to have an Explore mode, though Run 1's Adventure mode serves the same purpose.
There are currently 309 playable levels in Run 3's Explore Mode. It consists of the Main Tunnel, which has 65 levels, more than 20 side tunnels, two minigames, and cutscenes that fit between some levels. You can unlock the Skater, Lizard and Child by playing Explore Mode and reaching the conditions like clearing the Low-Power Tunnel or beating Level 10; the same goes for the Winter and Halloween Costumes.
Story
The plot of the game happens in Explore Mode. The story starts after beating Level 10, and progresses with each cutscene or dialogue found by the player. Because all of the levels are not finished, neither is the story. You have to beat Level 10 to unlock Infinite Mode.