I'm not gonna lie. I finished this on Normal difficulty back in the day and it was hell. When I saw that you needed to finish the game on Hard to watch the real ending, my child self was like "whaaaaaaa?".
Years later I did it with cheats. I don't care. The difficulty in this game is so cruel, arcade level. I think is way too much. I appreciate the cool ideas they implemented and the non-stop action, but after a while it gets really frustrating.
The first original Contra still remains as my favorite.