Offline Racing game idea

I want to make racing game just for my brother and myself so , I don’t want to make it really complex, I want to do it so that it have some CP opponents to race with him in laps, drag race, etc. it have some different cars to play with different environment. but I want to make it little interesting so that he doesn’t get bored of it quickly, like how Fortnite have building mode. like something unexpected. So, if you guys have any good idea can you share it with me.Thanks :wink: