Actually me, along with woc and some other people, have osu!mania "TP" project before.
But finally, woc decided to terminate this project (and switch the project into another feasible solution).
What we found is that, using a universal number to calculate for difficulty, is not feasible for osu!mania because people are having too diverse ability, which means the same pattern may be too easy for one player but too hard for another one, vice versa, despite of they having nearly the same skill level. In one word, to accurately calculate the difficulty of the map using only the patterns with one universal numbers is not fair at all, and to sum up multiple numbers doesn't make sense.
TBH our temporary solution include human work (a lot of them), and use player's past performance data other than patterns itself to determine the difficulty.
So far my suggestion is to make this as SIMPLE as possible. It doesn't need to be accurate at all, but being simple is OK. Even star difficulty along with some slight modifier on patterns is OK - because you may find it even harder than osu!tp to keep balance with these patterns.
But finally, woc decided to terminate this project (and switch the project into another feasible solution).
What we found is that, using a universal number to calculate for difficulty, is not feasible for osu!mania because people are having too diverse ability, which means the same pattern may be too easy for one player but too hard for another one, vice versa, despite of they having nearly the same skill level. In one word, to accurately calculate the difficulty of the map using only the patterns with one universal numbers is not fair at all, and to sum up multiple numbers doesn't make sense.
TBH our temporary solution include human work (a lot of them), and use player's past performance data other than patterns itself to determine the difficulty.
So far my suggestion is to make this as SIMPLE as possible. It doesn't need to be accurate at all, but being simple is OK. Even star difficulty along with some slight modifier on patterns is OK - because you may find it even harder than osu!tp to keep balance with these patterns.