The rarest cape in Old School RuneScape (OSRS) is currently the Music cape. As of 26 February 2020, only 11,543 players have achieved this cape of accomplishment. This makes it the least common cape in the game.
The Music cape is unique compared to other capes of accomplishment because it is not tied to any particular skill. Instead, it is obtained by completing various music tracks and songs throughout the game. This requires players to explore different areas and complete specific tasks to unlock each track.
Achieving the Music cape requires a great deal of dedication and time investment. Players must thoroughly explore the game world, visiting different locations and engaging with various NPCs to unlock all the required tracks. This can be a daunting task, as there are over 1,000 tracks to be discovered and unlocked.
What makes the Music cape even rarer is the fact that many players focus on leveling up their combat or skilling stats rather than dedicating time to exploring and completing the music tracks. This means that the number of players who have achieved the Music cape is relatively low compared to the number of players with high-level stats in other skills.
Personally, I have not yet achieved the Music cape in my own gameplay experience. While I have focused on leveling up my combat and skilling stats, I do enjoy exploring the game world and discovering new areas. However, the Music cape is still a goal that I have yet to achieve.
The Music cape is the rarest cape of accomplishment in OSRS, with only 11,543 players having achieved it as of 26 February 2020. Its rarity can be attributed to the fact that it is obtained through completing music tracks and songs rather than leveling up a specific skill. This requires players to dedicate time and effort to explore the game world and unlock all the required tracks.