Ico is an action-adventure game developed by Team Ico and published by Sony for the PS2 in 2001-2002. It also received a HD remaster developed by Bluepoint Games on PS3 alongside Shadow of the Colossus in 2011. After being captured for a sacrifice and then locked up in an old castle, the titular boy manages to escape confinement. A short while afterwards, he runs into a strange girl named Yorda who he can't understand. Together, they try to make their way out of the castle while being hunted by shadow monsters.
The description I wrote for the intro summarizes a lot of the plot of Ico. The game is very minimalist with its story. All the essential pieces are there, but anything beyond that has been willfully left out. There's a hero, a companion, a villain and not much else. As such, the game leaves you with many questions, like the history behind the castle and the sacrifices, but I find such questions pretty easy to fill in myself or downright ignore. Ico and Yorda's relationship is pretty understated as well, as it isn't allowed to flourish much due to their language barrier. It's a neat little dynamic though, even if they don't try to talk often for obvious reasons.
It's a very short and serene (or perhaps melancholic) experience to play through Ico, in no small part thanks to the excellent soundtrack. The castle is desolate, but not without signs of life thanks to the odd bird here or there. With the nice bloom and cloth effects plus the weird machinery dotted around, the castle manages to avoid getting stale in spite of how monochromatic it is. It being a singular interconnected map (cut up into "rooms", because 2001) helps as well, since you pop back into old areas every once in a while. With the indirect story and interconnected map, it's no wonder that this game got Hidetaka Miyazaki into game design. Hell, there's even some Ico DNA in Uncharted, what with all the climbing and AI partner interactions. Shows how important the game is to the medium.
The main conceit of Ico is pretty brave for its time. While there is combat and a lot of box-based puzzles to solve (inviting Zelda comparisons), the whole game is basically an elongated escort quest. Which sounds terrible, but since the game is actually designed around it, it works. Yorda doesn't really move unless you call on her, which then lets you take her hand and drag her around. So if the monsters capture her, it's because you left her in a bad spot.
The main gameplay loop involves climbing around and interacting witth the environment in order to make a path for Yorda, who can then open locked doors for you. Sometimes, you also have to help Yorda climb or clear gaps as well, actions which showcase some nice animation work. The puzzles are inventive, but with how hard the game goes with trying to be immersive, it can be difficult to parse what things are related to puzzles. There's no HUD and beyond video game-y items like blocks and bombs, stuff you need to interact with often blends into the environment. That is an accomplishment of course, but sometimes the game is a little bit too clever for its own good.
While I'm complaining, I need to bring up that Yorda's AI isn't perfect, so sometimes she doesn't behave the way she should. This is only ever a problem during certain puzzles where you need to manipulate her in order to progress. So if you're unlucky and she doesn't respond to your idea properly, you might dismiss that puzzle solution, even if it is the correct one.
Also, while I don't think the combat should be more complex than it is (thwack things until they die), I think the game would be better off if every combat encounter with shadow monsters were only half as long. The challenge lies in protecting Yorda (since Ico can only be slapped to the ground), but once you've understood where the shadows are spawning from and guided Yorda to a good spot, it's just a matter of thwacking them until the game decides that you've defeated enough of them for this room. It just takes so long unless you pick up the game's very hidden secret weapon.
Now, there are rooms where you can run to the exit to escape or have Yorda kill everything by opening a door, but unless you know which rooms these are, running for it is very risky. And there are certain sections where getting a game over means you have to replay a lot before you get back to where you where, especially if you missed a save point.
Even with that jank in mind, it's a lovely little game that exceeds in many areas where other games fail, even to this day. It shares elements with many other games of course, but I haven't played any other game that offers this particular blend of mechanics, presentation and theming.