A proper port of Street Fighter II, which is essentially the bible of many 2D fighting games.
This game is legendary, and for good reasons that go well beyond just being at the right place, at the right time. Compared to SF2, almost no one talks about the prequel, and for good reason: the controls in that game sucked, frankly. Try doing a hadouken or a hurricane kick with either Ryu or Ken in Street Fighter, without looking up how exactly you're supposed to input the commands for those moves. Shoryuken? More like "sure you can..."
On the other hand, Street Fighter II nailed how the controls are supposed to feel. Walking is comfortable instead of awkwardly hopping around. Jumping towards your opponent, or away from them works well. The commands for special moves are mostly easy enough. Zangief's spinning piledriver is mostly a no-go for me, but hey, there's a huge risk and reward with trying that move. In fact, that leads me to an aspect where Street Fighter II does very well: the characters!
Ryu and Ken are back from Street Fighter, but you have a much bigger cast of characters to play with than in that game. Sagat returns as well, and is playable. Now, he has a sick scar on his chest, and that's part of the backstory to the game. It's more than just a heckin' tournament, everyone has something going on. Sagat is looking for revenge because Ryu gave him the horrible scar with a shoryuken in the last tournament. Chun Li is a new character, who would become a legend* as far as female characters in fighting games go. Her story is that she is after Shadaloo, the evil organization responsible for her father's death. Don't worry too much about how exactly Shadaloo works, they are big bad guys who are the last four opponents you will face while trying to reach your character's ending: one of them is Balrog, an evil boxer who was banned from the sport for killing an opponent, and using illegal maneuver like his headbutt. Another one of them is the aforementioned Sagat. Vega is the Spanish masked fighter with a claw, and the big leader, who is the final boss of the game, is M. Bison.
(*) No, that's not meant to be a reference to that awful Hollywood movie about Chun Li. Please don't watch that movie, it's not even in the "so bad, it's good" territory.
Pretty much all the characters function differently, and more importantly, they feel differently when you fight them. That last bit is a fantastic detail, it's like Capcom felt the need to give each character a personality that is felt in the game. Wild. You may have to learn some quirks about the AI, but hey, in this case, it feels like you're merely learning how to beat the game, and how each character works. It's not like, say, Mortal Kombat II where you have to limit how you use characters due to an excessively cheap AI that directly reacts to everything you do. Ryu, for example, famously fires a lot of hadoukens at you. If you somehow don't know what a hadouken is, don't worry, you will learn very quickly after one round with Ryu. That's not to say that the AI in Street Fighter II is free from cheap tactics, though...
To summarize things up a bit: the AI from the arcade game is in this port of the game, however, let's backtrack a little bit. I got way into what makes Street Fighter II special but silly me, I didn't even talk about the first menu screen you'd see in this port!
"Champion" will send you to a game mode that is a direct port of the arcade's Street Fighter II Champion Edition. Just enter Game Start after that, and you'll have the same experience. The other modes are 2-player battles, one on one (V.S. Battle), and team battles (Group Battle).
"Hyper" is a mode that lets you change the speed of the game, gives different color palettes to characters and adds a few new moves.
Personally, I wouldn't recommend going past 2 stars of speed. I also would not recommend playing this at very high difficulty settings (not in Champion or Hyper mode). This isn't even really a matter of taste, the game just becomes unfair at the higher difficulty settings. Your attacks become weaker, and the AI opponents will have nearly perfect reactions to you, along with being overpowered due to the difficulty. Just trust me, stick to medium or around that level of difficulty.
Graphically, this port is beautiful, it doesn't lose much of the charm from the original arcade game. The soundtrack is also handled well by the Sega Genesis. That said, there is one little issue: if you only have a 3-button controller, ditch that. Get a 6-button controller so you don't have to keep switching between punches and kicks via the start button.
I'm essentially writing this as a reminder of how much this game nailed everything needed, and how it inspired so much. Great characters, controls, stages, soundtrack, a variety of countries represented. Sometimes, we (video game fans) take a lot for granted, and even moan about meaningless dumb stuff while losing sight of what's actually important: is the game fun? I had a lot of fun going back to this game and remembering the quirks of each character's AI. I also remembered that some games tried to do this kind of fighting and failed spectacularly. Go on Youtube and search for Shadow: War of Succession on the 3DO. You will laugh at how that game came out after this port of Street Fighter II, on a stronger system, and absolutely sucked at even getting characters to move around comfortably. None of the characters from Shadow looked nearly as cool as any of the ones in SF2, the only useful characters to use in Shadow are the ones with broken projectile attacks, none of the stages in Shadow are nearly as memorable as even the worst one you can think of in SF2, and though Shadow's soundtrack isn't the worst, it pales badly in comparison to SF2's.
This game is 5 stars, it set the stage for many future games of its kind. It's like the bible, or the ten commandments of 2D fighting games. Number 1 for me would be "Thou shalt not have bad controls" - you can fill in the rest yourself.