Depending on your other specs, maybe, but I've had some games simply crash immediately when I had insufficient RAM. I believe RAM is where all the floating data for a game is stored; stuff the game references on a constant basis. So if your RAM isn't sufficient, it might simply crash the game. At best, expect your computer to be eeally slow while playing.
RAM can be fairly affordable to upgrade, if you have a little free money, though I understand many people don't. If you happen to have enough to work with, there are some special considerations when purchasing RAM that should be taken into account, so make sure you've researched those, but the actual installation is usually pretty simple. Might be worth doing if you can afford it!
