Eternal Fort

Eternal Fort is an area and the final boss arena in B3313.

Description
Compared to the beta version of the stage which is a short and linear pathway to the Bowser Arena, this version is an actual course, with numerous traps and baddies seen from the official Mario 64 Bowser levels. Waiting at the end is the Koopa King himself, whose arena is much more dangerous now thanks to the added presence of Bullet Bill Blasters. Defeating him by throwing him into the mines 3 times as usual will award the player with the Big Star, and grant access to the game's Ending.

Origins
The area's layout seems to be an original creation, with textures taken from the beta version of Super Mario 64.

The area's music is a track made by Bobstar.

Plot significance
Bowser, one of the supposed main villains, appears in this area. However, him not saying anything besides a vague threat after being defeated makes his intentions ambiguous. Defeating him lets Mario/Luigi collect the Grand Star, which leads them to the ending.

Defeating Bowser:
YOU'LL PAY FOR THIS. ..

LATER!

Bowser after being defeated in ACT 1:
I THOUGHT THAT THIS WAS MEANT TO BE MY WORLD. ..

MY EVERLASTING KINGDOM! YOU'VE REALLY BEATEN ME THIS TIME.

I CAN'T STAND LOSING TO YOU! I'M OUTTA HERE!

JUST YOU WAIT UNTIL NEXT TIME.

BWAAHAHA!

Stars
Aside from the Big Star, there is one extra Star that can be collected in this course:
 * Collect all 8 Red Coins.

Leading here

 * Randomized Realm: Jump into the pipe at the end of the linear section.

Leading away

 * (0.9) Monochrome Castle Grounds: Defeat Bowser and collect the Big Star.
 * (1.0 Official) Castle Grounds (Ending): Defeat Bowser and collect the Big Star.
 * (Unabandoned) Ending Room: Defeat Bowser and collect the Big Star.

Trivia

 * Due to the warp to Randomized Realm being inaccessible in 0.9, the only way to access this level is to take the warp in Peach's Floor that leads to Peach's Cell, which has a rare chance to lead instead to Eternal Fort (beta). From there the player must die in the level to be sent back to the pipe in Randomized Realm, which in 0.9 now leads to Eternal Fort.