What’s old is new:

“Mystic Realm is a level mod for SRB2 with over 30 stages, a bunch of secrets, and a lot of stuff to do. Being originally created in 2003 and last updated in 2006, Mystic Realm is one of the oldest SRB2 modifications. As such, many of the levels here will likely feel dated nowadays after SRB2 2.0 included far more interesting single player stages with far more depth. On the other hand, an insane amount of love and devotion was put into this, and while the stages lack in modern size and depth, they do still have it where it counts. If you’re looking for a bunch of moderately decent single player content or have a nostalgia for older versions of SRB2, Mystic Realm should last you quite a while.”

Forum topic and download link here.

And something about v2.1:

Work on v2.1 is not as quick as any of us would like, but work is being done. v2.1 will contain new ring weapons for use in SRB2’s first person shooter gamemodes (Match, Tag and CTF.) They are in the late prototype stage and unfit for public viewing, although you might find our choice of placeholder art amusing. Lets just say that many Crawlas and a handful of Goombas have been serving as makeshift projectiles and are not entirely happy about their predicament.