1) Time Stop
The biggest change is probably how Keiichi was shot at the end of Minagoroshi-hen. In the games, Keiichi was shot without anyone could notice. As soon as it happens, Hanyuu suddenly freezes the Time. Rika doesn’t understand much, and Hanyuu basically let them know the truth. Soon, everyone notices Keiichi’s wound.
Due the Time Stop, they CAN’T move, they are barely in the same situation than Hanyuu’s: they are watching, powerless to what is happening.
Keiichi realizes it as well, and talks about his “retiring speech”.
This change is most likely a UP: Basically, the Time Stop was kinda too corny, as it is forced for drama, but also “last speech of death etc”.
Death isn’t a concept of agonizing with people being able to have/tell things in the last minute. The anime was realist enough to get an unfair death dealt by the enemy, and not letting such slow moment.
The bad side of this part is probably a despair less effective than the game, where everyone were crushed.
Rika was probably the MOST affected by this, as she refused to go on in a world, where Keiichi isn’t present anymore. That’s what I would complain: Rika had so many fighting spirit because of our hero keiichi that his death should have create a giant catastrophe for her. She was only dumbstruck, and she almost looked more concerned about Mion than Keiichi.
Rika in the game wasn’t able to accept this, and even begs Hanyuu about it, wondering if it is really fate. Hanyuu had no choice but saying she has to forget about it, and it will be possible to retry.
In that same aspect, Keiichi apologized to Rika in the end, about his retiring, because he knew that he brought many things about “beating the crap out of fate”. And ironically, he is the first one to fall in the clutch of fate.
he acted manly in the end again, assuring it is over for him, saying it is alright ashe is dead for now, but asks everyone else to beat the crap out of Takano.