Mega Man Zero 3 is set in a world called "Neo Arcadia" that has been created as a utopia for humans and Reploids (robots). This new chapter continues the adventure of the series' title hero, Zero and his Reploid allies in the Resistance group who are fighting for peace. In Mega Man Zero 3, Zero encounters a malevolent new Reploid called Omega who has unleashed the evil power of the Dark Elf to brainwash the Resistance in order to take over Neo Arcadia. As the only one who has escaped the brainwashing attack, Zero must fight to save his allies and Neo Arcadia.

Unlockables

Mini-games
Fefnir Mini-game - complete all missions with 100 points

Harpuia Mini-game - use zet zaber from the opening to the end and finish the game with an S rank

Leviathan Mini-game - complete all missions with 100 points

Phantom Mini-game - use buster shot from the opening to the end and finish the game with an S rank

Misc. Unlockables
Ciel mini-game - Beat the game with S ranking on all missions.

Copy-X mini-game - Using your previous save game, finish the game again in Hard Mode

Hard mode - Beat the game once, highlight new game at the main menu, hold L and press Start

Ultimate mode - Collect all of the secret disks, beat the game, then restart by holding R and selecting new game at the main menu.

Zero mini-game - Finish the game once

Secrets

Change Enemies In Cyberworld
First of all, get a MegaMan Battle Network 4 Red Sun or Blue Moon. You will need two GBA/SP and a GBA link cable. Go to Ciel's room in the place you go to after killing Omega. Press up in front of the computer. Go to Transmission. In Red Sun/Blue Moon, go to Comm. Go to trade chips and trade any chip into Zero 3. In Red Sun/Blue Moon, you will get a secret chip. In Zero 3, all Cyberworld enemies will be changed.

Fight phantom
On the second last level, go into the first hyperspace portal. Next, while you are riding the platforms, you should find a door. It leads you to 2 disks and a portal.

When you go into the portal, you will fight phantom from Megaman Zero 1.

One tough final boss battle: