how can i make a holiday system change something in the game in construct 2?

like, in halloween, a witch's hat appears on the character, or at christmas, a christmas hat appears

will you understand? if yes can you help me?

I think there’s a third party plugin to get the date. You can find a list of plugins somewhere on the forum or I think you can find it on the add on exchange part of the website.

Or you can use the browser object with a little bit of JavaScript to get the date with this expression:

Browser.execJs("let d=new Date(); str(d.getMonth()+1)+'-'+str(d.getDate())")