[Tuesday's Trope is a weekly department highlighting an amusing video game trope from TVTropes. Aggrogate is not affiliated with TVTropes.org in any way. All trope examples come from TVTropes and are shared via the Creative Commons license.]

Sometimes the biggest challenges in games aren’t actually part of the main story. You have to go out of the way, explore a bit, do some tricks for the privilege of fighting the biggest and baddest bosses. These are Bonus Bosses, and they’re one of those things that keep you coming back to games even after you beat them.

Examples of Bonus Bosses include:

• Mortal Kombat was arguably the Trope Maker, with the first game having Reptile as a secret boss. There is a very small chance that he will appear before the fight begins and give you clues on how to find him (ex.”Look To La Luna”). You can only fight him if, on the fight at the Pit stage, you don’t block, get a Double Flawless on your opponent, and finish them with a Fatality. If the conditions are met, the screen will flash with the words “You have found me, now prove yourself!” appearing, whereupon you will be taken to the Bottom of the Pit to fight him.
• Demon Supreme Overlord Baal in Nippon Ichi‘s Marl Kingdom series, La Pucelle Tactics, Disgaea, Phantom Brave, Makai Kingdom, and Disgaea 2. In fact, most Nippon Ichi games let you fight characters from their other games as bonus bosses, and they’re always at obscene levels. Laharl, Etna, and Flonne from Disgaea are all Bonus Bosses in Phantom Brave, for example. In many cases, defeating them will recruit them into your party. While the final bosses of the games tend to be at level 90-100, the bonus ones usually start somewhere around level 1000. That’s start mind you. In “Etna Mode” of the new Disgaea PSP remake, Baal is literally level 9999.
• Ruby Weapon and Emerald Weapon in Final Fantasy VII.
• Ultima and Omega, or Ultima Weapon and Omega Weapon, appear in many of the games, including Final Fantasy V, Final Fantasy VI, Final Fantasy VIII, Final Fantasy X, Final Fantasy X-2, Final Fantasy XI, Final Fantasy XII. Omega also features prominently in Dirge of Cerberus: Final Fantasy VII. Ultima was a mandatory boss in Final Fantasy VII as well as Final Fantasy VI, under the name Atma Weapon.
• Bonetail in Paper Mario: The Thousand-Year Door is literally more powerful than the game’s final boss and requires going through 99 battles to reach him. There’s also Atomic Boo, but that one’s a bit easier.
• Akuma is usually a bonus boss in the games where he isn’t the True Final Boss, particularly in Street Fighter Alpha 2 (as Shin Akuma) and in X-Men: Children of the Atom.
• Culex from Super Mario RPG: Legend of the Seven Stars. He appears as a boss character you’d expect to find in a Final Fantasy game although he has never made an appearance in one.