This game has been made by push, the Japanese SmileBASIC user.
Key: 4KE3VJA6
Almost all descriptions in this game are written in Japanese, but I believe it'll be no problem to play this game.
To Adventurer:
The photo which you have attached on my post is tutorial stage for beginners. (In Japan, the leaf symbol with green and yellow stands for beginner.) There are some standing signboards which are written as follows.
Let's go toward the upper-right ladder.
Let's check the upper-left switch.
Watch out for pitfalls.
You consume oxygen under the water.
...and so on.
