It's a bit of a strange plug but given how much attention has been thrown at various high profile fangames which all seem to be coming out at the same time (Enderal, Pokemon Uranium, AM2R) there's actually been a very ambitious Ace Attorney Fangame that was just recently released.
It's called
Conflict of Interest (link goes to court-records.net forums), and it's made in some weird software designed only to program phoenix wright fangames called Pywright. It's a full length Phoenix Wright game, about maybe 30 to 40 hours to play it to completion (depending on whether or not you turn on debug mode to allow for text skip, which you should, because the text speed is molasses). It's not a game that is indistinguishable from the real product, as it wears its fangame status on its sleeve. The original characters look rather MS-painty at times, all the music is just re-used PW music or stuff from other games thrown in. They didn't even bother updating Maya's sprite, but they at least use her appearance for jokes.
The story is an alternate take on Phoenix Wright's return to the courts after the end of AA4, and feels more like an extension of AA3 than AA4 at times since Maya comes back as the main assistant again. The biggest praise I can give to this game is that the writing is amazing and completely captures the tone and style of the Ace Attorney games. All the contradictions make sense, all of the cases seem insurmountable at first and there's no glaring plot holes or inconsistencies in the story that I could see. There's also nothing glaringly stupid, like MASON or weird gimmicks that don't really make alot of sense. There's a ton of great emotional moments too, not just the whole triumph feeling that Ace Attorney can give you at the end of the case but the writing is very effective on pulling your heartstrings.
On the flip side it doesn't really do anything new with the formula, besides some very minor tweaks. Like, absurdly enough, even the case-by-case review feels like an old PW game. It was a throwaway shit first case, a really interesting and cool 2nd case, a weak 3rd case where they threw in all the annoying witnesses, and an utterly amazing unforgettable climax in the 4th and 5th cases also with one of the best final villains (that doesn't overstay his welcome *cough AAI cough*). Some of the problems with PW, like dragging on investigation parts, also feel exacerbated by the increased length of this game.
And the biggest, near-fatal flaw in this game is that it's simply too absurdly hard. It's not that the contradictions are complex, there are a ton of non-obvious roundabout contradictions but they all make sense when they're explained in universe and kind of feel obvious in hindsight. The actual PW game has tons of these, this fangame's actual mystery elements are only slightly more complicated than the average phoenix wright case. But the PW games usually try to telegraph it pretty obviously, like they'll start a hypothesis and then expect the player to finish it. This game just doesn't seem to give a shit about easing it in. Like characters will have a long discussion about needing to prove X, and then the green prompt from the judge will literally be something like: Present your Decisive Evidence! with literally no other hints. The third case in particular requires you to present I think 4 pieces of evidence in a row, without any indication you're on the right track, and if you get one off the game doesn't even tell you which ones you got right and you have to try all over again. Worse yet sometimes a detail (like say WitnessA testified about the murder weapon) which will occur during the case will not actually be updated in the court record. But you're still expected to point it out whenever a witness contradicts a statement about evidence that wasn't even in the court record.
I had to consult the included-guide about 3-4 times a case because I was just utterly stumped.
That being said, if you are okay with accepting defeat sometimes, the writing in this game is really good, basically indistinguishable from the actual Ace Attorney games. It has everything you love about AA, but also everything you hate as well. I'd easily rank it above Dual Destinies for how much enjoyment I got out of it, and I actually really liked DD. In any case, it's definitely worth checking out.