Custom Controls: in the settings menu, have the ability to change the controls to the players preference. E.g: Arrow keys instead of WASD
Robo Parts and the Elevator: in my opinion, if a part of a robot falls on the elevator, and when it is activated by the player, the robot body parts should deteriorate or disintegrate instead of just vanishing when they reach the bottom.
When you have all the Upgrades in Endless: so, Some people are pretty pro at Endless, Right? I know of a person that got to level 100 on Twitch mode with over 200 active viewers. So, I think that there should be some sort of prize for getting to so high into the game E.g. at level 50 you have the option to get a small buff like 85% faster jetpack or if you killed a certain Robot using a certain weapon above a certain level you can get a 6th clone or something like that, because there is currently no reward for getting to the higher levels in endless.
Thank you for reading.