Kudos for making a game using code only! It's nice to make a game where you understand what every line does instead of a game engine where you are building on the shoulders of giants using prefabricated functions and features.
Regarding the game itself, I played it about 3-4 times. A few observations:
-- It's not really clear what is being looked at in the main screen. It appears to be an enlarged version of the robot face?
-- I noticed the targeting reticle moves, but I'm still not sure how that relates to selecting the right missile. Do you have to fire certain missiles when the targeting reticle is in certain spots?
-- I figured out that the 3 bars are the Player health, but only after several playthroughs of trial and error.
-- I was able to beat the robot once. I guess I got lucky that time!