Hi !

A web build of the game is required for mutiple reasons : it's easier to play as you just have to click on Play and it already works, also because we don't all the have the same operating systems (Windows, MacOS, Linux, various distros) so it gives a lot more compatibility, and finally, people that want to play and rate your game often will not take the risk downloading executable programs from a "non-trusted source", like their fellow jammers.

You can of course upload both Web and Windows build.
But I strongly recommend you to make a web build because else, you game will not be eligible because most of the judges don't use Windows, so they can't run .exe, and because you are gonna get very few plays during the voting period.

Do you have any specific reason of why you don't want to make a web build ?