The main problem I detected is that the detection of a key pressed or joystick movement is very laggy, at the point that it is near impossible to get the edges of the frame without lost a life. The same to avoid the Fryolites. A part from that (I think very important) the game is OK. Fixing this detection rutine is would be fantastic.
Despite the border being 1px wide the whole 8x8 area is the collision zone which can give the impression that the game hasn't responded to input. This isn't how I would have designed it, but it is part of the original design from 1983 so I kept it. The control system feels a lot sharper on a joypad btw which is how i play it (Xbox One controller on Fuse, Switch controller on Retrogames The Spectrum). It's supposed to be fast to make it tricky :). Keyboard input is checked every single game loop, one game loop = one step.