Still a cut above the rest
The game allows for stalking maps via rooftop, or any other method you would choose to infiltrate, and reaching an objective assassination target. The system is similar to MGS in that being spotted alerts enemies who in groups can be very formidable, and it hurts your end ranking. Also like MGS are the alert systems, once an enemy has been alerted to your presence they will take an alert phase, a cautious phase, and a calm or unalert phase. Where Tenchu really shines is the weaponry, very era appropriate, it is excellent and every piece has a good use when mastered. The unlockable content for getting grand master on every level is also pretty extensive for a game of it's time.
This all being said there are some downfalls, like the crouched movement controls are tanky (to be expected of the PSOne age though) and sometimes the assassinations get muddled up in the actions of your enemies, leaving you open to a spear in the side. All this aside, this game is basically the blueprint for Assassin's Creed, so if you like assassination style gameplay Tenchu is a good old school pic.