You follow Gaster into the next room with some keyholes on the door and keys scattered throughout the room. 

“Little one, this place is my lab.”

“My ‘true home’ as I like to call it. ”

“Anyway, I would like to let you know a few things before we proceed. My full name is W.D. Gaster, but you can just call me Gaster.”

“Now, here in the underground, we love our puzzles. Allow me to show you how they work.”

And so you do.

~~~

You follow Gaster through the many puzzle rooms. He guides you through the first few puzzles, teaching you what to do. They don't seem to be physically demanding, which is nice. Instead, they focus on one's problem-solving skills. It doesn't make sense at first, but Gaster waits patiently, gently explaining how the puzzles work.

Eventually you start to get the hang of it, and Gaster allows you to try a puzzle on your own.

Walking into the next room, you're met with panels of conveyor belts covering the floor. You take a cautious step onto one of the panels. It seems fine, so you move forward to the next panel. As soon as your foot touches the belt, you feel yourself moving as the panels activate, pushing you back to the start.

You glance back at Gaster, silently asking for a hint. He gives a gentle smile. "It's alright, little one. Remember, trial and error."

You nod, and turn back to the task at hand. You step back onto the first tile, and it remains still. This time, you tap your foot on the tile to your right. It doesn't move. Letting out a breath, you move onto the new tile.

The puzzle takes a long time, but eventually the effort pays off. You make your way to the other end of the room, and finally step off the last panel. You excitedly look back to Gaster. He's smiling at you, and he looks... proud. He walks across the puzzle, following your path, and joins you at the end of the room.

You look up at him, beaming, and he chuckles. "Well done, little one!" he exclaims. "Are you ready to try another puzzle?"

You nod excitedly, and the two of you step through the doorway, to the next puzzle.

With each room, the puzzles feel easier and easier, and each time you completed one, you’d look to Gaster and see a proud look on his face. 

~~~ 

Eventually, you come to an enormous metal door. Gaster walks up to it, and gestures for you to follow. He punches in a code on a keypad beside the door. The heavy doors hiss and slide open.

“My child, this place is very special to me. This is my home, and now it's yours too.” 

The door hisses open. You and Gaster step inside.