I played this game “co-op” on stream with Brad (rainwarrior), and I had a lot of fun! It seems like the crowning achievement of many years of NESdev learning. It’s a lot of fun to see the gradual ramping up in gameplay, graphics and design improvement from H:H85, to H:H86 and H:H87.
By the way, for the “co-op” explanation: a second controller can tag in and take control of the characters. This works pretty well except in the shmup sections where there is no controller tagging out. If you’re playing with someone else as I was, when you’re running low on health it’s kinda fun to say, help help, tag in, tag in! And they do and you get to see how they’re doing.
H:H86 also had this feature, but it was also not really mentioned in the manual or game itself.