Main thing, why I disasmed Captain on NES is that I wanted to continue my older hack (the one with reworked upgrades and a silly additional level) and improve upon it. I caught a nasty bug in my original coding of Hawkeye's trick arrows and, overall, it'll take a long time to do (both by itself and due to fluctuations in my motivation). So, for now, my thoughs and a couple of mockups.
Basically, after you finish the game, you get 'World 2', now with the whole world instead of USA.
In France, you jump on highway from car to car, trying to catch up with Georges Batroc.
In Russia, you go through a resident building (or several), trying to stop Nuke (get it, they dropped Nuke on Russia).
I also have some vague notions on reworking upgrades once again, but nothing concrete.