In-universe, do you think someone created Tempestra?
 

Or do you see her as a real creature from another dimension?

I would like to know the story behind her creation. Some disgruntled game developer must have programmed her to come to life when the player reaches the final level. Whoever came up with that idea must be REALLY angry at society for him to program a game sprite to wreck havoc once it is free.

You guys have any fan theories about Tempestra?

I have my own idea on that one.
http://forums.thetechnodrome.com/showthread.php?t=54339

I assumed it was a malfunction at the arcade caused by the lightning that made her come to life.

In the episode "Night of the Rogues" it was revealed that she was from Dimension-X, so perhaps it was an idea of Krang's. He probably figured "Those bothersome shellbacks are teenagers, so they must love video games."

Was it? Antrax was said to be native of that Dimension, but I do not recall Tempestra's origin being explained further than her breaking free of the game upon someone actually beating the impossible to conquer game coupled with being struck during an electrical storm.

I think Krang released the game through anither front than Shredder.

Well considering how that game was impossible to beat... This guy maybe?
https://upload.wikimedia.org/wikiped...mbs_Up_MNT.jpg

I believe it was programmed by some programmer who got rejected from a videogame company.