OpenTTD has a window with Detailed Performance Ratings. https://wiki.openttd.org/en/Manual/Detailed%20Performance%20Rating

I've tried to get it to 100% but I've always struggled to do so, as I was never able to have no vehicles turn a loss. I think it could be interesting to have a 100% and 90% category. I personally don't find the normal plain No-NewGRF 1M% to be very interesting, so perhaps it could be interesting to see if people could be interested in achieving a score of 90%.

Note: because of the different economies, this would need to be separated by climate, because I think the experience will be sufficiently different for it to matter quite a bit which climate you're playing on.

Besides, that would stimulate some people to try and go for arctic or subtropic.

I'd say have the same rules as Default Settings NoFF. Game starts upon world load, and ends on the first frame when the Detailed Performance Ratings window shows 90% or 100%, depending on the category.

Already try 100% too, but was struggling to overcome 90%, when i open old saves, everyone was at 90%, i have no idea what to do.

So have both categories would be cool.

i tried today, will take probably over 3 hours without FF, and the cities take to much time to grow, need to study more to understand how to quickly grow a city

I tried it out. Getting to 90% took me a little over 3 hours. With the default settings you have to connect almost all primary industries to secondary industries.

Although I did lose a significant amount of time on fixing jams, and thinking about what to do next.