I think a feature that would be cool is if you can add a "comment" to a beatmap which can appear at the beginning of a song which reminds you of that one tricky slider or that surprise double note that always catches you out. It could just be the placement of an exclamation mark or something, the timing of appearance which can be personalised. I know this is a bit complicated and hard to achieve but it's just a thought I had 
Let me know if this idea is terrible XD
Let me know if this idea is terrible XD