Hall of Infinite Doors

You continue down the hallway. Nope. No food. There isn't anything remotely edible. There aren't even any doors here. Just a lonely tombstone sticking out of the ground. Most of the inscription is worn off and it's impossible to tell who was laid to rest here. There is, however, a newly-carved portion near the bottom of the stone. The letters are crooked and the spacing odd and broken, but the letters are legible. It reads,

<i>IST TH
HIS END?</i>

As if in answer, the floor in front of the stone cracks as soon as you finish reading. A rectangular portion of it falls into the abyss beyond, opening a way downward.

You turn your attention back to the hallway and realize it isn't much of a hallway anymore. It ends just beyond the tombstone. You find yourself staring at a white wall with the text, 'Time to add to the adventure!' scrawled across it.

You spot a sparkling keyboard nearby and feel a wry smile dance across your lips. This isn't the end. After all, this isn't the Hall of Finite Doors...