Urban Scholar said:
Hell at least that would've made sense as to why he went on a rampage as a villain. With two one good and one bad and memory loss, etc. Ugh my head hurts. Follow toku gaf if you have links as to why stuff was changed like this and etc please link me. Now I want to rant further.
Basically, as far as Decade's finale goes:
-> Main Producer originally announced that All Riders vs Dai-Shocker would be the show's finale, taking place after the tv show.
-> At some point, they changed plans, decided to make a post series movie to be the finale, and moved All Riders vs Dai-Shocker to take place before the final arc of the tv show in a rather sloppy way.
-> The final movie was originally announced to be a double feature with separate Double movie and Decade movie. They were "All Riders vs Decade" and "Double: Episode Zero". The teaser for the movie that aired alongside the finale was originally recorded right alongside the final episodes of the tv show, so it was a teaser for "All Riders vs Decade". The movie went far enough into production that it was even listed by some theaters, after the tv show had already ended, before being replaced by...
-> Finally, we ended up with the triple feature Kamen Rider x Kamen Rider Movie Wars 2010, with Decade: The Last Story, Double: Begin's Night and Movie Wars 2010 proper. During all those changes, the scale of Decade's movie was clearly scaled down (not an All Riders feature anymore, so many Riders cut, including Stronger, so they had to change Tackle's story too, but still use her somehow because they already had her new suit made).
-> On top of that, Narutaki was seemingly meant to get some kind of monster form (some material for Movie Wars 2010 still references his "hidden combat potential"), even when the project became the final Movie Wars 2010, but the suit somehow wasn't made. As a result, he's just written off during the final battle of the movie, rather than getting any closure.
However, having said all that, Decade going around killing all the Riders would always happen. If you rewatch the earlier Decade episodes, they keep reusing Wataru's words in the first episode about Decade killing everyone to save the worlds. Narutaki even talks about Decade killing every Rider and then dying himself in the original tv show finale. It was always meant to be there. The other Tsukasa presumably would have a role closer to Doras in the final movie, as leader of Shocker, just to have
someone around for a final battle with all Riders fighting alongside each other, after fighting against each other early on, rather than having anything to do with the whole destruction/rebirth story.
