I have all 3 of the Alien Breed games on the PS3. I beat them all, they are really good. Was just curious, is this the original, and the ones that I have are remakes. Or are these entirely different games with different stories?

The new ones have a different story and better visuals but the same kind of gameplay. The ones on here are the originals but feature different stories.

I think the best way to experience the originals is to get the recent PS3/Vita release (released on February 6th in EU and will be released on February 12 in the US), simply titled Alien Breed. It's a very authentic port of the original Alien Breed plus the Special Edition '92 version (which was only available on Amiga), with different levels. It's also got the original Amiga music, which the GOG version doesn't have, and, well an "enhanced mode", with HD sprites (which I'm not too fond of), remixed music and modern dual stick shooter controls, closer to the 2010 Alien Breed Trilogy.
The GOG version of this was pretty disappointing in my opinion.

How? It's the original Dos versions. It's exactly what I was expecting from a GOG release since their job is re-releasing games, not pimping up stuff.

Not many people actually played the DOS version of the game. You can be sure that 95% of the re-buyers of this game will know it from the Amiga, which was infinitely superior to the ported DOS version (the first one was at least - Tower Assault was a very respectable port).

The PS Vita version is fairly faithful to the original Amiga game, although it makes a few tweaks that dumb down the game a bit (strafing, for one) that I don't really like.

So in a way, I agree with fisk0 - GOG would have done better to try and release the Amiga version (discussions about the feasability of this still ongoing on the forums) instead of going for the massively inferior DOS version.

How is it massively inferior? Sure, both the audio and the visuals are a little worse (I'm surprised that even the resolution seems to be higher on the Amiga judging from two videos I just compared) but as far as I can tell it plays pretty much the same, my first reaction certainly wasn't "bleurgh" which is more than I can say about some other DOS ports GOG has to offer.

Am I missing some crucial details, massive flaws in terms of gameplay which aren't apparent when only taking a quick look at videos?

hm. I had Alien Breed on Amiga back in 90's. I remember there being also AB2, and thus titled, and that was the king of shooters back then for me. I remember then trying some PC version later, only found AB1 and some semi-sequels or something. Later again, downloaded AB for PSVITA, from PS Store... I gotta say, it's alright. But the best way to get AB would be to download Amiga Forever and install that, then get AB1 and AB2 or order amiga from amazon or something :)
Hey, the differences are not THAT big, all the versions are fine I'm sure. Haven't tried gog version, not sure how that plays. But if you are a fan, all I'm saying, might be worth a check to get Amiga Forever Emulation (I think it was about 35 euros or something.)

to clear a bit: Amiga ver. of Alien Breed 2 had this amazing idea about firing: the character's gun when fired, only showed the flame of ... you know, the shots being shot at the end of the rifle or whatever, then there was no actual shot animation. The place where the shot hit, that's where there was animation. And I gotta say it was somehow amazing new idea. The "new" PSVITA version (or the collection of odd versions) does not have that.
AB2 was something, aah. :)

Don't take it too seriously. Might even get that gog version some of these days.

Alien Breed 2 Amiga (AGA) version in-game: http://www.youtube.com/watch?v=CrhOePgThQ4
if that port for PC through gog.com was possible I'd vote for it, but I don't think it is...
I mean just thinking that it would have to be ported to PC first, then tested with various configs etc.... and who'd do all that?

This thread inspired me to dig up the Amiga version and play it via an Emulator and compare it to the GOG version. Gameplay wise I feel they are pretty darn close, of not identical, although I didn't play deep into both so I can't say for sure. The main difference is that, as expected, the Amiga version has better sound. If you compare to the '92 enhanced version, well that's a different game altogether. And for the average user playing the GOG version will be much easier to accomplish than somebody downloading an Amiga emulator, digging up a kickstart rom, etc etc etc.

I think if you really enjoyed the GOG DOS port and want more and Tower Assault doesn't fill your needs then definitely dig up the enhanced version or Alien Breed II for Amiga.

The trilogy released this past decade is a reboot not a remake, it's the same Team17, albeit with a modern team and studio, but it's a new story and a completely new engine. Only the premise is the same.