I had an epic one last night and I just remembered it now as I'm eating my melted Jarlsberg swiss cheese sandwich and coffee.
It was a take on the Marvel Ultimate Alliance games, except it was in 3D and not top down. It was incredibly epic. I was switching characters and flying around this open world with Iron Man, over a big ocean and shit, and then I had to choose a path...the one on the left seemed safe and the one on the right had these two massive ogres, like SOTC-sized colossi, and I of course chose that side. I took them down by firing missiles at a gigantic ferris wheel that was right behind them for some reason, which then fell on top of their heads and crushed them.
At the tail end of the dream, I "finished" the game and there was a free-roam bonus after you finish it and I saw Sev, Natko, Garza and Rico from Killzone 2 flying through a massive building.
At the very end, demi popped up in the dream, but not as demi, as the guy in his avatar and I told him that the game was an easy 1000 achievement points and then I woke up...