Great work! This is my dream come true!
(Although the Intellivision version is the one me and my mom played the most during early 80s)
BTW, would you be able to adjust the controls to be more forgiving while going up/down ladders and pushing left/right simultaneous as you did with Donkey Kong?
Currently moving on a ladder with Up/Right or Up/Left or Down/Right and Down/Left halt the character from moving.
Although this could be by game design, it is very unforgiving on the controls.
I would suggest the character to keep moving towards the direction pressed and as soon as they reach a platform that allows left/right to continue to the platform.. in other words there should be no halting on movement while more than one directions are performed on the controller.
For example, Down-Right on a ladder should move character down until they reach a platform level and then the character should move off the ladder (even if the ladder continues) and move right on the platform.. while on the platform and still holding Down-Right, they should keep moving right until they reach a ladder and then climb down.
You followed a similar logic with Donkey Kong, and it works perfectly!
EDIT: I tried a version on MAME and it does halt movement with 2 inputs. So this request is probably a feature improvement.
My experience was more with the Intellivision version which does slide/keep moving
BUG: I noticed on your version walking up and down ladders is a bit off-centered, and can also climb a pixel up/down while near a ladder and not entirely centered on it.