'Core' is a game that allows players to create their own intricate games within it, share them online, and play online. It's in open alpha now.

How do we define what is a "core" Mario game and what isn't? You probably think the answer is obvious and are developing your own list of "core" Mario games in your head right now.

Core has teamed up with Multiverse Games for a special event as they will be throwing their own Summer Games this Sunday.

Core is a free, PC-based game development tool, similar to PS4 game Dreams and Fortnite creative, that aims to make game creation more accessible, much like YouTube and Twitch did for video.