I'm doing a roleplay called "Of Friends Turned Foe" with Miss Saffy. It takes place starting just pre-Great Game, and we're not sure when we're going to end it yet. The story is primarily Johnlock with a side of Mystrade, but we are now looking for a Moriarty to come in and mess things around a bit for everyone. We are planning on working through the episodes, though with changes appropriate to our own storyline (no real major events planned far in advanced, sort of a feel as we go along style).
Entering scene for Moriarty is coming up right now in the time line, with him posing as Jim from It at a Scotland Yard Charity Dinner. Mycroft is in attendance, but unaware of Moriarty's real identity. After this, we can discuss how soon we want to move into the Great Game plot/ how involvement will work in the future.
Let me know if you're interested, can't wait to add a new person to the story!