I've enjoyed playing through a second time. Here are some suggestions:
The death reload scene is too abrupt. Add a transition of some sort or give the robot a death animation like the enemies have. The large size of your scenes would make panning the camera back to the starting point a good type of transition to use.
The enemies can still kill you if you run into their zapped out of existence animation. This added some challenge but doesn't seem intentional.
Starting over at level one when you run out of bots is frustrating. Instead, reload the current scene so that all bolts and enemies are back in their starting positions.
It would be more informative to the player if the bolt counter started at a set number and was decremented so that we know how many bolts are still out there.
I recognize that this is a demo of sorts. You'll have to judge whether what I have to say in this next part is worth the extra effort or not. The trip back to the teleporter is dreadfully boring. Some sort of "make it back to the teleporter" phase of the game feels necessary. This would mean the player doesn't just mindlessly pick up the last bolt and head to the teleporter. He mentally prepares himself for what he is about to trigger. It makes for a more memorable gaming experience. Some options I can think of are:
-A new wave of enemies.
-Previously inert security traps such as lasers come into play.
-The lights go out. Light up robot with a spotlight. Leave the teleporter lit, like a beacon in the dark.
-A timed race back to the teleporter. Maybe a gate shuts on you if don't make it in time and you have to fight a horde of enemies to unlock it.
-Upon collecting all the bolts, the robot's jet-pack initiates and he is able to fly back to the teleporter. This introduces a new game mechanic and makes the trip back a fresh experience.
My final suggestion is to enable the arrow keys as an alternative method of movement. In your movement code you can add an "or" statement to the keys that you define. If "w" or "up" is pressed, etc. Thank you for making this game and for hearing my suggestions!