Well, it's good to know you don't have an addiction problem. I sometimes get something sort of similar, where if I've been playing a game a lot (usually a simple puzzle game like Tetris or minesweeper) not long before going to sleep, I'll actually see spontaneously generated game situations in my mind's eye and I'll also see the pieces move as if I'm trying to solve the puzzle at hand. None of this happens voluntarily, not even the active puzzle-solving part. I suppose you have something like this but just in a much more acute form.
My guess is that it has something to do with learning-- the brain is trying to take in all this new information, make sense of it and internalize it. It has been shown that when people first try out Tetris, many different portions of the brain are active at once (roughly corresponding to a higher involvement in conscious activity) since they have to pay close attention to what's going on, figure out how to play and what strategies to use, get used to the game in general, etc. When experienced players play Tetris, only a couple of small, localized regions show up as having more activity than usual-- the task of playing Tetris is no longer novel and so no longer requires full cognitive resources, but rather has largely been taken over by unconscious brain processes. In other words, the task has become 'automatic,' just as, say, tying your shoe is now automatic for you. You don't have to think about it or pay close attention, you can just do it on autopilot, so to speak.
So my best guess at what is going on here is that after you play these new games, your brain is very much in the process of learning how to play them, what to expect in certain in-game situations, and in general getting familiarized with the game overall. Learning seems to work by first recruiting wide cognitive resources (many of which are implicated in consciousness, such as attention, subjective sense of effort, etc.) and somehow using this whirling cauldron of activity to create dedicated, specialist subsystems in the brain that can eventually take over and do the task automatically (unconsciously) without requiring many conscious resources. So perhaps your brain is caught up in such activity, but for some reason the learning process is reactivating, or overactivating, those parts of your brain that lead you to consciously experience playing the game (whereas for other people, the brain might be working on all this learning stuff after playing the game, but on an unconscious level). There are hypotheses that one function of dreaming sleep is to help the brain sort through recently acquired information, integrating and storing the relevant stuff and discarding the rest, which relates to my above speculations and might help explain why this is happening in your sleep.
I really don't know why it should disturb your sleep patterns so much, though, beyond generally being more stimulated than usual. Are you a light sleeper in general? Do you tend to experience vivid dreams or vivid hypnagogic or hypnopompic imagery?
I'm also not quite clear on your 'sleepwalking' episodes. I get the impression that a few minutes after falling asleep you wake up and find your hands are moving as if you were holding the controller playing the game, is that correct?
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