Galerians: Ash

Different ending:
Finish the game in normal or hard mode.

Hard mode:
Finish the game in normal mode and reach "B" or higher rank.

Enable short mode:
Finish the game in easy or normal mode, after save.
Load back the cleared saved file.

Lv3PK mode:
Finish the game in hard mode and reach an "S" rank.

Extra skip:
In the Enriched Uranium Refinery, in the room where you format the security card
to "Saturnus", beat all the gray and red robots after you talk to Ash over the
security screen.