Laptop won't charge while playing The Sims 3

@choidimas  The confusion about whether your computer is plugged in or not sounds like a mechanical issue with either your battery or your cord.  Check the cord itself—does it have any bends or creases where the wires might be coming apart?  How does the plug look, and the socket on your laptop?

Or this could be a battery issue.  Something internal could be starting to fail, with the battery indicating that it's not receiving charge because the overall charge is decreasing despite it being plugged in.  TS3 is fairly energy-intensive, definitely more so than TS1 and TS2 at least, games in general drain the battery faster than almost anything else.  If your battery can't charge as quickly as it used to, or if it can't hold a charge as efficiently as before, maybe it can't quite keep up with the demands of the game.

But really, this is the kind of thing that you need to have evaluated in person.  Whatever else TS3 might be doing, this isn't an install issue so much as a problem with your physical components.  It's fairly easy to switch out a laptop battery, and yours is old enough to be due for a replacement.