I'll begin working on one soon, just as soon as I finish my current one ;D
Time travel... I don't know how to do it :/ .... Suppose I could do a mirror of the mission "Night of the comet" or the one befroe it... where you play your mirror self... do stuff... and screw up the timeline :O
Don't forget, 'In a Mirror, Darkly' showed that inter-dimensional travel isn't always locked Temporally.
The players character could be sent to negotiate with the Terran Federation but ends up in the 'WoK'-era in the Mirror Universe, you witness the Klingons begin invading Drozana and K7. Then try to make contact with the Devidians of that universe in order to negotiate a way home; (Their help).
ATTENTION:UNDINE SPACE & TKON GROUND SETS ALL THE WAY DEVS!.. Q-TRIBBLE, MAYBE!?.. EJECT WARP CORE ABILITY LIKE LAYING A SUPER-MINE, HELL YES!!!.. SPACE HIPPIES FROM TOS PLAYING MUSIC IN OUR FLEET STARBASE, NO, JUST, NO... CAIT & RA'KHOLN ADVENTURE ZONE, YES