Oreimo PSP suggestions:

1. The True Little Sister Big Extermination: Sistercalypse?
I thought "taisen" meant "great war(s)". But even if you change it to that, it still sounds kinda awkward.
And why Sistercalypse, when "Siscalypse" is what Kyousuke says? "Siscalypse" pretty much says enough about the game, anyway.
"Official title is The True Little..." blah blah blah - May I suggest "The official title"?

2. "Although it looks like an RPG..."
I heard Kyousuke say "adventure game". This might be okay, but I think he would still explicitly say "RPG" instead of "adventure game" if that's what he meant.

3. order.record.effect
In the part that introduces this, might want to capitalize the first letter of each. Though, I haven't seen the original Japanese, if it was like that previously, or in katakana.

4. Saori: "Let's find players on the SnS!"
I thought the N was capitalized too, because it's part of an acronym. But I don't know what it stands for.