And the AI may have been a lot simpler, but that's part of the reason the game was a much tighter and smoother playing experience. Not to say the later games are worse because of the AI or anything because they're not, but MGS very much plays like a game that knows what it's about and does it extremely well, while the later games have much more breadth to them as far as what you can do which is also cool, but leads to a bit more of a balancing act from designer and player. A balancing act which hasn't always worked so well (tranquilizer gun in MGS2, the stealth and action dichotomy in MGS4).