First time that I beaten it without cheats (so getting the special ending) I passed through all areas. I started on the last area and followed routes passing from sor2 until ending on sor1 headquarters. I though the special ending was because of crossing all the game. I was shiva and plaid solo.
If I want to go mania for a fast&furious play I go shiva and an aggressive Mr.X partner with players damage off, so we do great combos together. The drawback is that an aggressive partner ruin my bosses repetitive moves and we die a lot
When I want to play for serious I go shiva with balanced rudra.
When I want to play for score I do solo.
I'd like to ask an extra question: what is your highscores? My best one was mania solo no cheats and didn't die any credit. Btw are scores cumulative when dying credits?
Also I think the highscores should tell if the player used cheats or not.