It can be anything you want. Dress up as Han and Leia (as Luke and Leia would just be wrong), or get married on the bridge of a makeshift Starship Enterprise. If video games are more your thing, adorn yourselves as Link and Zelda and cut into a Triforce-shaped cake.
your theme will dictate the style of your wedding, so think carefully about
where you'd like the ceremony to be and what you want it to look like. For
example, a green and purple indoor "Halo" wedding might not be quite
as nice as outside gold, green and white "Legend of Zelda" nuptials.