Don't fall down and search something like a plank or a diving board
that lead to the middle of the room. Walk along this thing and climb down the ladder.
Down there your first boss fight awaits you:
BOSS # 1
So you find yourself in some kind of underground adit with 6 pathes. 3 on every
side. You can't enter any of them, the splitworm though can enter them and slime his
way through them.
The worm always comes out of one of the 2 middle pathes.
He always sticks out his slimy body and then opens his armor. Then you can see his
mouth with very very big tongue.
This is the moment where you fire some bullets onto him.
You will only be able to shoot like 5 or 6 bullets than he closes his armor again. After that
he smashes on the ground. So you better take cover and/or get away from him before he
does that. If he hits you you will lose way more health as when he just smashes on the
ground somewhere else.
He will reappear now on the other side. And he does the same thing again.
After 10-15 hits you are done with him.
Easy isn't it?
After the bossfight you are back in the normal reality.