I know there is a lot but I personally think you guys would like what I have in mind so please do read it if you have the time.
I hope/wish there is a TMNT online adventure, role-playing game, where you could choose to either start as one of the turtles and then at some point you can switch charcters, including to Splinter. Or, you could start out as "Shredder's daughter" Karai before she found out and could go through what she must have went through as his "daughter". You could do side games, like train foot soldiers, and train to get an "allowance" for new ninja outfits and awesome weapons and accessories that you actually get to wear and not just get the attributes from the item. The same with the turtles with the side games but more along the lines of better weapons, maybe even some funny weapons, maybe EVEN unlock Ice Cream Kitty (as a weapon!). It would also be awesome if we could unlock the mutanimals and if you are soooo good at the game and unlock everyone and everything, maybe even unlock Shredder, Tiger Claw, etc. for the bad guy fans, and Apirl and Casey, Bishop, the Salamanderians, etc. I'd personally would be Tiger Claw for the bad guy. And after I'd unlock them, I'd probably play as Mona Lisa, the Commander, or Bishop. But I'd probably need more than one save file so I could have one as Miwa and one as Splinter.
There could also be a rank system where you would start off as "Puny student" and then work yourself up to "Master (or Master's Pet since the Masters are still there)" and get outfits and weapons based on that rank. Splinter would really only have one rank that he could gain, "Grand Master" and would be the hardest and longest time, rank to gain (same with Shredder). You could also just explore the city if you want as which ever person you are. Of course there would have to be a great storyline, graphics, and character designs like the 2012 version...and many, MANY adventures and missions!!!!
I won't write a whole essay but I just think it would be TOTALLY AWESOME if this existed.