Can be gotten here: http://www.zvitor.com.br/projeto/mfa2.html
It's really more of a remake of, than a sequel to, the previous game, which in turn makes that game outdated.
The controls include the following buttons: attack, jump, special, & block. You can combine jump and attack(no left/right alternative though). Some characters can fly, or web swing, or whatever, by pressing block mid-jump. Flight is essentially gradually descending from the point of the jump after you've hit the button. You can run by double tapping left/right, for a running attack, or a running jumping attack. During jumps, depending on the character, there may be a new move for pressing up & attack, and most will have a new move by pressing down & attack(not necessarily a diving attack like a lot of other beat 'em ups, though some will). On the ground, the special button, which requires a full meter (which gradually fills, if you don't grab a blue orb to help it fill up faster), will usually provide a crowd clearing move. The range being dependent on the character, as this is often the best display of their power. Alternate attacks include pressing up, up & attack to do the same move that ends your characters strike combo, which is always a knockdown move, when you need one. Quarter circle forward & attack is often a good display of a characters power as well, as characters with ranged attacks will generally use them through this move. Sometimes it's even different depending on the status of the special move meter. If you should happen upon a "marvel comics" icon, down, down & attack will summon a character to temporarily help out for a moment. Characters with a power level of 5 or 6 can walk into enemies and grab them, for either an attack, or throwing them into enemies behind them. Ant Man will show up in the first stage to go over the special moves anyway.
I believe the only object you have to manually pick up is a radio, which summons a character to help out until their health is depleted. Though if a character has a Leadership stat of 1, no one will show up to help. Everything else, including the previously mentioned blue orbs, is picked up automatically by walking over it. These include red orbs, which restore a bit of health, yellow orbs which restore a bit of health and the special meter, medical kits, which restore a character to full health, and Stan Lee icons, which are 1-ups, and usually hidden(certain points on your score will increase your lives as well).
You start the game off with the following 16 characters: Jubilee, Wolverine, Beast, Jean Grey, Cyclops, Hulk, Thor, Iron Man, Captain America, Mr. Fantastic, Invisible Woman, Human Torch, The Thing, Black Widow, Hawkeye, and Spider-Man. More will becomes playable when you reach a new level, or certain check points within levels. One even become playable(for other modes), after you've beaten the game.
The game itself runs a bit long, for the genre, at around 3-4 hours. You can leave the game at any time, and pick up where you left off by selecting "Load Game." This is useful if you find you've lost a number of lives, but haven't completed the section you're on, so you can try all over again. If there's a teleportation device on the ground (white metallic object with blue and white flashing light circles), you can walk into it and choose another character.
Once beaten, new modes unlock, offering plenty more to do. 3 of which are based on SNES Marvel games(2 were also on the Genesis, one even having started as an arcade game, but it becomes evident which versions were used as the basis), as well as 3 original modes, a Replay mode(choose a character, choose a stage), Danger Room(a practice mode), Versus(a 2-4 player fighting mode), and Hard Mode, which allows you to use any character at any point of the game, though will not save your progress as you make it to new stages, like the main game. There's just a ton of variety for this game.
The downsides include:
-Since up/down are used to change palettes, character selection is used with left/right, on a screen that can have 54 characters to choose from...
-Sometimes it just tosses too many enemies at you. Especially toward the end, when there's a scene where it tosses a good number of boss characters at you. As long as you know the best move to survive you'll be alright, but it's still a bit much.
That's really about it, it's a pretty good OBoR mod if you're a fan of Marvel Comics, as it give characters that aren't usually playable in officially licensed Marvel games their chance(plus you can play as some villains/grey area characters).