So, I've never actually played Castlevania II for the NES. But I loved the first one intensely. However, I watched Egoraptor's Sequilitis about the two when that first came out. I did however play Dr.Jeckel and Mr.Hyde which I think he mentions in his video. This dream kind of used ideas from both of them. It was so disturbing while I was actually in it so I guess you would have to see it to realize how scary it really was, even though I didn't wake up scared.
Me and my girlfriend were playing some game that I can only assume was on the NES. We were killing some monster things and I got a message that said "What a horrible night to have a curse..." which is the line that would show up in Castlevania II. My character changed and started going after my girlfriends character. I told her to run because I had no control over him and he was going to kill her. Something happened and the game turned into a first person view type thing, except we were actually in it, because we had full control over our bodies. We were exploring and grabbing different kinds of weapons that were laying around but as the sun set, the message popped up again. "What a horrible night to have a curse...". Instead of me changing, a whole bunch of horrifying monsters were appearing around me. I pulled out a handgun that I had found while searching and cocked it. I didn't cock it all the way and only one bullet went into my "ammo". I fired one bullet at a time having to cock the gun each time I wanted to fire. I can't even explain what this creature looked like...it was like a rotting heap of flesh with a head. I shot a few bullets into it's head but it didn't seem to be doing anything. While that was going on, there were other horrifying things running around, and I wasn't sure what to focus on. Eventually, I learned the correct way to cock the gun and was given a complete clip of ammo each time. Even after firing an entire clip into the monsters head, it didn't seem to have any effect. I was thinking to myself "what kind of game is this?". Eventually, the morning came and all of the monsters became peaceful or vanished. There was a town nearby that me and my girlfriend ended up at and some of the shopkeepers were goblins. Though they would be hostile at night, they seemed to be friendly now. I realized that what I would have to do is hide when the night time came. I was out exploring in the field again, when the message popped up and night fell. I found a barn that was littered with skulls and bones and hid somewhere completely out of site. I saw some goblins approaching and they somehow knew I was there. They began to light the barn on fire with flamethrowers and I began to burn alive. It was horrible and I remember thinking that I was just going to let myself die because I didn't want to play anymore. Right when my health was about to run out, it filled about a quarter of the way and I exited the barn. Outside, I started fighting and killing the goblins, blowing them up with some wagon full of explosives. I continued to walk and found a few more horrible monsters that I started to fight with some bladed weapons I found. The combat felt so awesome, but I was hardly doing any damage. The last thing I remember was trying to get away from some horrible giant half-dead troll looking monster with tentacles. I remember jumping down a well to escape from him.