Has anyone had a dream where you played a video game that never existed in real life or hasen’t been released yet?
Yes, several times. A cross between Settlers and Sim City shows up often, and I really enjoy playing it…especially planning and constructing transport in difficult terrain.
Played a bunch of RTS, sometimes a weird mix of existing ones like AOE II and Rome:TW, or Dwarf Fortress 
, or downright new levels of old games 
Also played an 8-bit horror platformer, a new 2D mario game and several 3D ones, a FPS arena game (mainly Bioshock-like), some Smash Bros here and there, Sims levels, sparse turn-based stuff, not to mention some of the craziest RPGs I’ll ever meet 
including Final Fantasy-related scenarios, and Okami-related 
Plus some others I can’t remember at the moment. All this in non-conscious dreams, though. Only one made me lucid, mainly because it was some HI during the WILD process.
I played a videogame Mario-alike. 2D. Taken straight from Mario world, but with different colours and dimensions to it. It acted like a training ground for dream-control for me, and I’m thinking of trying to cobble it together in the real world with a programmer I met during the Global Games Jam.
Also, Tosxy. You’ve played Dwarf Fortress? I got obsessed with that for about three weeks and then had to go cold turkey on it. Don’t think I would play it for huge, huge lengths of time, but it’s such an interesting piece of work with so much depth to it. Probably keep checking it whenever it’s updated.
Yes, last night even It was some kind of 2D RPG, it looked pretty cool. I was a character in green and then met another one that joined the party, in a village. I don’t remember anything else though… But I’ve played some weird stuff…
Yeah, I’ll check next update myself too, that squad stuff is sounding promising.
Also, gotta say, I felt so good while playing that DF derivation, it was so inspiring. That game really got me at that time, and still impresses me to day. Of course, it got romanticized in my head with time 
but I really liked the concept and the execution. Hope some good soul will develop some 3D graphics in some years 
I was playing some sort of game called, “Unbeatable Battles.” (Which, is the title of an actual game that I’m planning to make. The dream version was a whole lot different from the planned version.) It was a 2D sidescroller.
The player character was in a house. Apparently, there was a glitch that enabled you to go underneath the house, into some sort of beta room. The room had enemies that never appeared in the game. One was some sort of metal arch that shot out pulses that hurt the player.
Some time later, the game changed entirely. The player character was changed into a bug (Literally a bug, not a glitch.), and he needed to turn into a human again.
I’ll be writing the full dream in my dream journal.
I once dreamt that I played a demo of Metal Gear Solid 4 about three months before it came out.
I rage’d so hard when I woke up. 
I had a dream a while ago. Like the game carnivores. It’s an old fun game. Except the dinosaurs were different The creatures didn’t exist. It was actually pretty fun
I’ve had quite a few Dwarf Fortress dreams too, some in glorious photorealistic 3d. It seems I’m always having fun in those dreams…
I heard that the ‘superheated rain causing dwarves to melt’ bug has been fixed recently, but what I’m really looking forward to seeing is when the kinks have been ironed out of the new medical and military options.