To any company, the remake is one thing that begins to make the mouth water, and for good reason. The sole purpose for a company to exist, naturally, is to make money. A remake, or classics collection, depending on how it's done, is one of the easiest ways to do so. You take the best of what's already been, as most of the work has been done the first time around, and generally add a few extras, then put on a bargain price, and finally put it on the shelf, ready to find a new generation of fans.
Except, whether they see it or not, there's an art to remaking and collecting.
There are generally four schools of thought to this, and let's take a look at them.
Some, such as Super Mario All-Stars and the to-be-released-but-excessively-named Super Street Fighter II Turbo: HD Remix, recieve graphical overhauls while the core gameplay is untouched. The former is very noteworthy, as it was the first well-known both remake and collection, and has almost become a classic in its own right. The latter is more controversial, but getting alot of fan-based feedback, and more importantly, still in development. It should go without saying, then, the jury is still out. This is, in my own opinion, the way to go.
Another way to reviving a franchise for another go without too much hassle is an amalgamation. This is more prevalent in fighting games, and it involves taking a series with alot of tweaks to it (see Street Fighter II and Darkstalkers for examples), and then allowing the same characters to have different gameplay styles and the player to mix and match them at will. This can take some work, but when done right, and with respect and detail paid to the source material, it can be an entry in its own right. Of course, it can also fall flat on its back, especially when it's done in a rather rushed manner or makes one standard the one to follow (see Mortal Kombat Trilogy).
And now, we move on to the more-or-less ports, bundled together. This is true of smaller-sized games, like Mega Man Anniversary Collection (and it's Mega Man X-based sequel). This train differs from the mere collection in that extras are generally included, and consist of content that can't be had easily anywhere else. For example, all three versions of MMAC included ports of both arcade games the franchise spawned (Mega Man: The Power Battle, and Mega Man 2: Power Fighters), which saw very limited release outside of Japan.
Then, we get into the straight collections. Most of the work here comes in programming the console-based emulators, and then the original code from the original console is run through it. While this makes for the truest experience, given that some differences will remain, I feel it shows laziness on the part of developers, and even more when there's speculation not even the emulator itself was written from scratch, as there has been with Sonic Mega Collection. Also, unlockables tend to be either more emulated games, or maybe some art.
And finally, just finally, we get to where I believe the term 'remake' is tarnished almost forevermore, the steaming pile dropped on the Game Boy Advance called Sonic the Hedgehog Genesis. To anyone that has played this and thought it represents the actual experience, I'd like to apologize, and point you toward the above-mentioned Mega Collection. Almost all of the code was rewritten from scratch, and it shows.