Harking back to early PC video games, I'd love hidden routes or short cuts in the open world. These could be unlocked by entering a sequence at a specific time on a route (e.g., near the chalets, you enter left, left, right, right, left and turn abruptly onto said off-road trail and discover something new.

Honestly, if it takes, you'd have folks touring around the world searching for these. It could also integrate easily with Zwift Play or any other cycling controller.

From there, you could make it ok in informal group rides to take short cuts. This might be more fun for the mountain bikers among us, but when I race friends on trails, we say it's ok to take whatever route down you feel best about.