this very great, but idk how to do the main route on the first "choice"

I love the idea of there being different routes in a game. But also with the theme of portal make it just 100 times better. I would really recommend adding new music for a different kick. But if you want to keep the portal 1 music, that's okay. Anyways to get this portal game for free is like a dream come true. Also i like that there is a tank, basketball court, and voice boxes scattered around the facility. But there are some cons.

I cant find a way to beat the 2nd chamber in deep in rust. So i always have to use sv_cheats to move on. But the are also some smaller cons. like the floating boxes in channel. And the "should" spelled as "sohuld"

Other than those cons. This game is perfect

Edit: I really recommend you to put the map selector in the bonus maps. Sence it does not have any impact on the main game.
Edit 2: i think you should remove the button and the cover in chamber 2 of Deep In Rust. If you just hop down in the hole it automaticly opens to prevent softlock.