I almost didn't make Day 18 due to the weather and other things going on. At 11:00 PM, I jumped on the bike and tried a route on Rouvy. There are some other virtual cycling simulators and Rouvy might be the closest competitor for Zwift but in my opinion there isn't really a comparisson. If they didn't have a Mac version for free I wouldn't bother because their algorithms that calculate climbing are horrible. On this route I was on a 4% grade and it felt like 20%! Even if I calibrate it.