Survival & Three-Minute Attack Modes
Beat the game under any difficulty to unlock Survival and Three-Minute Attack.
Double Daggers
Beat the game under any difficulty. Save after the credits roll, then reload the saved game to start with a double dagger.
Mini-games
To get survival mode, on one of the rooftops in the first level, there is a little screen in between two boxes. To get boss battle, you need to beat the game once and get the twin blades. After you restore power to the main elevator in the Wisdom HQ, if you go to the library on the employee's side, your can access the door, and just jump across the third level and it's there.
The Final Boss
Algla transforms into another monster. When he turns a color, change to the color of the weapon. It does the real damage to Agla.