Imagine if the movies of the Prequel Trilogy had been made in the same spirit as the awsome trailers of the new "The Old Republic" game. Youtube.com.
In such a "what if-version" the Galactic Republic should have battle droids and local security forces instead of clone troopers. Just as Obi-Wan says: "flying is for droids", Republic and Jedi policy should be "that wars are fought by droids NOT living sentient beings". The Republic should be extremely unprepared for war and relay entirely on its brave Jedi Generals and their massive droids armies.
The Republic Navy should include: Dreadnought-class cruisers, Hammerhead-class frigates, Consular-class corvettes, as well as, Droid-fighters and Delta-7 Jedi starfighters. In addition there should be many different local units, such as: Mon Calamari Providence-class cruisers, Niemodian Lucrehulk-class freighters, Phorax-38 fighters, Geonosian Nantex fighters, Noobian N-1 Royal starfighters, V-19 Torrent fighters and ARC-170 starfighters.
In this alternate version the Sith Emperor (the evil vengeful nemesis of the Jedi Order) would be as old as Yoda. The exiled Emperor and his followers should have been in hiding for almost a millenia (800 years), planning their vengeance on the Republic and its hated defenders. The Sith and Moffs should have perfected the art of cloning to re-create an enormous military machine, based mainly on clones of ruthless Mandalorian mercenaries.
The forces of the Sith Empire should include: Clone troopers in phase 2 armour, AT-TE walkers, AT-AP walkers, AT-RT walkers, AT-OT walkers, Destroyer Droids (droidekas), Mandalorian Commandos (Death watch), Imperial officers, Sith warriors, Venator-class Star Destroyers, Acclamator-class transports, primitive TIE-fighters and TIE-bombers (imagine mixing the ETA-2 actis-design with the Alpha-3 Nimbus V-wing-design). Grand Moff Dooku would be the leader of the Imperial war effort. Other major Sith villains could be Assaij Ventress, Darth Maul and Darth Grievous.
Episode I begins with Obi-Wan Kenobi and Qui-Gon Jinn on a tour of the Outer Rim, in a large Dreadnought-class Republic cruiser, to investigate rumours of a "Phantom Menace". While our heroes are on Naboo, the Sith Empire launches their surprise attack with massive fleets of Venator-class Star Destroyers spawning primitive TIE-fighters on an unprepared peaceful Republic. The Republic cruiser above Naboo launches it's Droid-fighters and engage the enemy, but the ship is owerwhelmed by the much larger invasion fleet.
Naboo would be one of the first planets to fall, as we see Imperial Acclamator-class transports deploying clone troopers and AT-TE walkers upon the surface of many worlds simultaneously across the Galaxy. Noobian N-1 Royal starfighters engage the Imperial invasion fleet above Naboo, just as the Grand Army of the Gungans engage the invading clone army on the ground. But the local forces are no match to the Imperials and they are easily defeated.
Jedi Master Qui-Gon Jinn is killed as he and a few battle droids manages to buy Obi-Wan, Queen Amidala and Captain Typho enough time to escape. Their ship is damaged during the escape and they have to land on Tatooine for repairs. Padmé Amidala and Obi-Wan (instead of Qui-Gon) encounters Anakin Skywalker, who helps them. Obi-Wan, Padmé and Anakin arrives at Coruscant just in time for Queen Amidala to add the last warship of the Naboo (her small flagship) to a large Republic fleet that is going to send re-enforcements to Geonosis. Episode I ends with a Republic victory on Geonosis. However, the Empire is still advancing everywhere else and the situation is dire.
Episode II would be about the adventures of Anakin, Obi-Wan and Padmé during a large scale counter-offensive by the Galactic Republic. The objective would be to liberate hundreds of the more than thousand worlds, which have been occupied by the Sith Empire in the interim period between episode I and II. Take a look at the Old Republic's "Hope-trailer" about a battle on Alderaan. During this succesfull offensive the relationship between Anakin and Padmé should bloom into a true love-affair. At the end of Episode II Anakin and Padmé should be married in a secret ceremony, just as they do in AOTC. After all, it is forbidden for a Jedi to enter into deep personal relationships, as they are the defenders of all sentient beings.
Episode III would beginn with Mandalorian commandos kidnapping Padmé Amidala from Anakin's bed on Coruscant and taking her to Mustafar. Anakin is incapacitated and given an ultimatum; help the commandos deactivate the droid armies of the Republic, from within the Jedi Temple, or Padmé will face a horrible death. Deep beneath the Jedi Temple Anakin enters the deactivation code on the central main frame computer and an epic Sith attack on Coruscant beginns. Take a look at the Old Republic's "Decieved"-trailer for inspiration.
A furious battle above and upon Coruscant follows and only a handful Jedi and Sith would remain alive after its over. Mace Windu is killed defending the Jedi Temple and only Obi-Wan on Utapau and Yoda on Kashyyk seem to be able to escape the Imperial onslaught, as the droid armies of the Republic suddenly shut down across the Galaxy. Defending Republic fleets orbiting Utapau, Kashyyk and other systems are hastilly recalled to defend Coruscant. Local starfighters are also requested to aid the Republic units defend Coruscant, as the Republic's Droid-fighters also have been deactivated by Anakin.
During the sacking and conquest of Coruscant, An unconscious Anakin is taken aboard the Imperial flagship above Coruscant. The Sith Emperor now offers the young Jedi-traitor (Anakin), who had caused most of his friends to be killed to save his secret-wife, a deal. It would be the same deal that the Emperor later offers Luke in ROTJ. Anakin can either choose to let himself and Padmé be killed or he could let himself be turned to the dark side. While the assembling units of the Republic Navy is being destroyed in the battle above Coruscant, Anakin chooses to join the Sith after having killed Darth Grievous in a duell, very much resembling the duel between Vader and Luke in ROTJ.
Once the battle is over and the capital world of the Galactic Republic has fallen, terrified Senators are forced to pledge allegiance to the new Galactic Empire. Anakin is allowed to fly to Mustafar aboard a Victory-class Star Destroyer to release Padmé from her Mandalorian captors. Here he tries to convince her to pledge allegiance to the New Order of the Galactic Empire. While, she begs him to leave the Galaxy with her, so they can escape the evil of the Empire. At this point neither Padmé nor Anakin knows that she is pregnant. Anakin even offers to surplant the Emperor and make her his Empress (just as Vader offers Luke to rule the Galaxy as father and son in ESB).
But their discussion is cut short as Padmé is saved in a rescue operation by Obi-Wan, Captain Typho, Jan Dodonna and other loyal Republic officers and pilots (who have decided to continue the fight against the Empire). Obi-Wan almost kills a furious Anakin during Padmé's rescue. Padmé goes into life-long hiding on Alderaan as Bail Organa's wife (remember Leia's memory of her mother being very sad in ROTJ).
At the end of Episode III Anakin (now as Darth Vader) and the Emperor could very well be the only two surviving Sith Lords. But with all the droid armies of the Republic deactivated and the Republic Navy destroyed, they would be in abolute control of the Galaxy.
However, the birth of Leia and Luke on Aalderan brings new hope to an enslaved Galaxy...
