Not too bad.
I think it's too empty, if you're at the base, where are the buildings?
Put cliffs and similar scenery around the area you what the player to be able to reach, to stop the player seeing the end of the landscape.
The story is a little odd (Stories are the hardest part for me )

)
Why does a plumber have a gun?
Why did the military choose him to fix the leak? (Wouldn't a dangerous military base be secret?)
I'd like to see you continue and improve this work
[to put images into a post, just make an account on an image hosting site. And use the (img) &(/img ) tags, with []instead of normal brackets

]
good frame rates matter... and a low ping might help XD