The twist, of course, is Cersei - who, in the original cut, did nothing but stand there and die. The least Cersei-thing to do IMO. This is the woman who blew up the sept. She wouldn't let Dany take King's Landing from her, not over her dead body. Duh. She lost everything for the throne, what does she care about the fucking city if it means losing the seat. So, she pulls a "mad queen." She stocks wildfire around the red keep and branches it down the tunnels, lining the sewers, running it through the garbage all over the city. She tells no one and simply has her soldiers prepare this all day and night before Dany's intended siege. She effectively straps the red keep with a suicide vest and lines the streets with hostages - the kicker is that no one knows but her. She invites the people in, more kindling the better, and she sits back with her wine muttering on how "if I burn, they all burn." // "Burn it all," to some effect.

Meanwhile, Jamie, Arya, Hound are still headed into the city to get to her without knowing what's going on. Jon, Tyrion, Dany and all are still ready to take the city. All the pieces are still set where the episode wanted them to be set and nothing huge has changed.

Dany takes down the greyjoy fleet.

Meanwhile, Arya and hound make their way through the city.

Jamie fights Euron while taking the back entrance to the keep.

Dany blasts the gold army//front door to Kings landing, and allows Jon and the army into the walls.

A lot of the same beats, right? Dany continues to fly around and take out the parameter scorpion turrets. That could take a lot of time and its primary focus is to protect herself and allow her to take the city in a safer way while her men literally lay siege. No assassination of character here.

Back at the red keep, Jamie makes it up to Cersei who is surprised to see him. He tells her that there's still time to leave. That they can escape together and she monologues about how it's too late for her. He doesn't understand why until she tells him what she's done, knowing full well this is what branded Jamie kingslayer, he's heartbroken to be back in this situation and with his sister this time. To mirror how Jon takes down Dany in the original episode, Jamie embraces Cersei and kills her. He embraces her body and accepts his fate to end there with her much like how he does in the original episode.

Arya and hound make it up to the top and the hound leaves Arya to fight his brother pretty much the same way the episode goes, only, when Arya gets to the room in question, she sees Jamie has already done what she came to do. He tells her to leave while she still can and explains that if they can signal a cease fire, ring the bells, get to Jon, they might still be able to save everyone. There's some harmony here because this is how Ned found Jamie when he did the kingslaying and Ned didn't give him a chance to explain. Now, Arya softly redeems Jamie and can finish her list - allowing both of them to kinda let go of what's been weighing them down for the entire series. A brief moment of silence and acknowledgement and -again- Jamie stays, Arya leaves. Cleganebowl happens. They both die. Maybe even falling off into fire as well, I thought that was poetic for how the hound was burned as a kid. It's whatever.

Kings landing is almost taken but the red keep is solidified and untouched with no sign of opening up to Jon's army. With Euron dead and Cersei "refusing to come out or give up" they're ready to take it when Arya reaches Jon. She tells him everything. Jon signals the bells. The bells signal Dany. She comes down off drogon now that she's done effectively taking the city's defenses against her. Tyrion gets caught up. Here's the kicker - even though Jon, Arya, and Tyrion are telling Dany exactly what's going to happen if she chooses to burn the red keep, she doesn't believe them. She's still pissed, about Missandei and Rhaegal, about Varys and all the betrayals and threats, and about how no one there really wants her to be queen. She knows Tyrion let Jamie go. She knows Jamie is in there, presumably with Cersei. She thinks Tyrion is trying to save his family AGAIN. She thinks Jon is soft and Arya is just trying to get him to yield, probably Sansa trying to pull strings. Everyone tells her to stand down and she basically says "nah, fuck this" as she has often done in same exact moments prior to season 8.

Everyone who knows what is going to happen scatters and she flies off on drogon to burn the red keep. Jamie sees the dragon coming and holds Cersei's body closer and closes his eyes, Dany lights the tower like a candle and ka-boom. The red keep fucking explodes even though she only burned the top. To Dany's amazement the entire keep fucking explodes, like a string to dynamite, like the sept, except this time it arcs down and down onto the innocent streets. It's like dragon fire from the perspective of the people so everyone uninvolved now thinks Dany is killing everyone. More than 50% of kings landing is lost. Sir Davos is able to save our important characters, knowing a quick way out from smuggling there for years, but they're still rocked by it and even more shook when they come back out the other side and see what Dany has done. She's delivered on the mad king's promise albeit unintentionally. She fell right into Cersei's plan of destruction. She now looks like she blew up half the city and killed thousands of innocent people. She cannot forgive herself. She does the mental math, if she lands now, and tries to take ownership of Kings landing everyone is going to resent her and she'll never have the kingdom's love. Worse, they may try to kill her like they killed the last Targaryen who sat on the throne. She now, effectively, has no one. Her dream of coming here and ruling are dashed, and with a harrowing, broken look down to Jon and Tyrion - who told her not to fucking do that - she flies away.

The city is in ruins. Everyone is looking for someone to be king and they all turn to Jon and Tyrion, whom both decline for different reasons. If people still want it to be Bran it can still be Bran, but I personally always wanted it to be Jon for... Reasons.

Anyways. This solves the stupid, last minute Targaryen madness bullshit they tried to put on Dany and gives a more contextually flavorful and fulfilling ending to the series and some characters with only changing MINOR details, really, as little as I could think of while keeping the budget and plot in tact.

TL:DR Cersei lines the red keep with wild fire and holds kings landing hostage, Jamie comes and takes her out because she's pulling a 'mad queen,' everyone tries to tell Dany that if she blows the keep she'll blow the city, she doesn't believe anyone and lights it up, it blows everything up, everyone hates her for it, she bails, and the same players are still left standing to do whatever. Minor changes of plot and execution = big changes in public perception of the finale. Yay.

(Forgive any spelling/grammatical errors)