Take a chess board. Add portals. Now you have Portal Chess.

The concept is fairly straightforward. Each side has their own portal, which they can move one step in any direction. Going through a portal means your piece's particular style of movement continues through your opponent's portal. There are a couple of other details and rules, so you should watch the full video for them.

Definitely going to try playing this one with my dad. Since, you know, I beat him that one time. And I may very well do so again.

How to play Portal Chess! [YouTube via Reddit]