I've been working on a surfing game on my spare time for the past year. The idea is to keep it closer to the real sport, focusing on pumping, carving, nose-riding, etc. I shared a video of it on the Unity3D subreddit[1] and the feedback was quite positive, so planning on getting a demo ready as soon as possible!
[1] https://www.reddit.com/r/Unity3D/s/mB2kn0BxIT