Shadow the Hedgehog is a game that you should play, despite how mediocre it is
The basic idea is: Hey, let's get our antihero, make him use guns, let the player be able to choose whether he's good or evil, and just make an overall cool game. In some ways, this intent pulls through. In others, it just falls flat.
To start, the gameplay is Sonic done as poorly as you can possibly imagine. Shadow is difficult to control in every way. A surprising thing is how natural the weapons (including machine guns, swords, bazookas) actually feel in the entire package. Yet, the new focus on combat is not appreciated. Fighting never was the strong point of the sonic series in the first place. And now that killing enemies can actually be an objective, you're exposed to just how bad the AI is, and just how awkward and easy the fights are. One of the most understandable, yet annoying problems in the game is how every "enemy" whether they're classified as 'good' or 'bad', is targeted by your attacks. Even more annoying is how, no matter what side you're on, both sides will still shoot at you. So, sometimes you'll be forced to kill everyone, and you'll hear your "buddy" say something like: "Hey, he's on our side!"
Oh, yes, and about these "buddies", the game comes up with different objectives most missions for good, evil, and neutral. One objective will always involve blowing through the level and not paying attention to everything, and that objective will usually be the neutral one. But, when you aren't on neutral, you'll get a good or evil person following you around constantly, saying stupid, repetetive dialogue. Sometimes, the objectives they give you can be fun and interesting. Yet they always end up being: "Kill all of . or destroy all of , or activate all of " This is actually fine, for the most part. EXCEPT when it is the forementioned kill all the enemies. When you get this objective, I heavily, heavily suggest doing ANYTHING else unless you've gone through the other parts already and the level that that path leads to is one of the few that you haven't completed. "killing all of the enemies" is extremely tedious and boring. The worst thing is that you'll always have ONE SINGLE enemy left, and you'll have no idea where he is.
Depending on which objective you pick, of which there will either be two or three, you'll go to either one level, or another, or another. This is probably the best feature of Shadow The Hedgehog. The interesting thing is that the game is really, really short. You can easily beat it in one sitting. This actually isn't a bad thing, because the feeling of accomplishment from that is great, and you know that you'll be able to come back again and play through levels that you've never seen before. Depending on your path, the story will also differ. Sometimes, it can end up being stupid, and not making much sense, along with not revealing anything about Shadow's past that we don't already know. Other times, however, it can be pretty good, for a game with bad voice acting and dialogue, that is. The main problem is that, because there are two or three paths leading to almost every level, the next level you go to will often make no sense. For example, you can very well go from Shadow invading the GUN fortress to him randomly appearing at Doctor Eggman's base. You could very well get a "story" of Shadow appearing in a bunch of random places. Still, it's cool that we get to learn about his past, why he was created, how he lost his memory, and even why he still exists after the end of Sonic Adventure 2.
Overall, if you're a fan of Sonic the Hedgehog, Shadow will interest you. It will disappoint you, but at the same time, it will interest you. Perhaps if more effort had gone into it, it could have been one of the most memorable entries in the Sonic series. Unfortunately, things didn't go that way.