The .mcr extension signifies a raw dump of a 128KB PS1 memory card.
A "complete" Tekken 3 save typically unlocks the following content immediately: Full Roster : Access to all hidden characters including Bryan Fury Julia Chang Heihachi Mishima , and the final boss, Secret Characters : Usually includes the tiny dinosaur and the elderly scientist Dr. Bosconovitch Bonus Modes Tekken Ball (the beach volleyball mini-game) and Theater Mode Alternative Costumes tekken 3 mcr save file
Note: In Tekken 3, characters like “Unknown” (the silvery, glowing Jin clone in Tekken Force mode) are not selectable in standard versus mode even with a save file. That requires a separate GameShark code. and the final boss