So you've never seen a game get reimplimented in an engine with qualty of life features you've always wanted or engine modernization so it'll actually run on machines past Windows 98?
That's never stopped anyone.

Yes, obviously, considering a reverse-engineered attempt at Dark Forces exists (but hasn't been finished last I heard). However it's not a source port by definition.

Maybe the Gothic remake will be one:)

This one, or one from actual studios?

The game that comes to mind for me is Metroid 2 for the Gameboy.

The game just isn't very fun on the original B/W Gameboy. The question for me is not "should you play the original?" but more like "which remake to play?" because there are 2 remakes for this game. A 2D unofficial remake for PC called AMR2 and a 2.5D official remake for the Nintendo 3DS called Metroid 2: Samus Returns. While I like both a lot you'll probably have an easier time buying the official version on the 3DS over finding a download for the unofficial remake since Nintendo did a DMCA takedown on all downloads of AMR2. Sucks because it truly is a very good game.

There is, however, one unique thing the original game did that isn't present in either remake.

As you may know, video game music typically repeats after a certain amount of time. Also, older video game music was not stored as a recording, but rather was produced on-the-fly. In order to make polyphonic sounds (in other words, in order to play multiple notes at once), the music was split into separate tracks, each of which plays on a specific sound channel (the number available depended on the hardware). Normally, every track would have the same period, starting over at the same time, so that the music would stay in sync.

In Metroid 2, later in the game the different tracks *don't* have the same period. As a result, one track would reach the end and start over, while the other tracks have not yet reached that point. As a result, the music goes out of sync, and ends up not being exactly the same as when you entered the area. This creates a rather unsettling feeling with the music, and is a technique I've never heard of being done before or since.

The two remakes, like nearly all modern games, just use recorded music, and as a result, are not able to do tricks like this.

There is a way to achieve this result using recorded music, but it would involve using extremely long tracks. The tracks phasing against each other is deterministic, so all you'd need to do is work out how long the track would need to run for before they come back in sync and export that.
For example, if you had one part that was 2 bars, one part that was 3 bars and one part that was 5 bars then it would need to play for 30 bars before it repeats. Obviously that's a very simple example, but you get the idea.

doom? i would say that people should play doom, but doom 2 is just much better

If you measure time not in bars, but in audio frames, and you have two parts whose lengths are both fairly large numbers of audio frames, and happen to be relatively prime, the length of the recording you'd need would be way too long.

A better approach would be to simply play multiple recordings at once, and expect some part of the audio system (either in the OS or the game engine) to mix them together.

Vampire: The Masquerade - Bloodlines is awfully glitchy if you play the actual original version.

The tank-like controls in the original Tomb Raider haven't aged well. Aside from quick-time events, Tomb Raider: Anniversary is an improvement in most respects.

Don't you usually specify a tempo when using a tracker?

Furthermore, if you can make the tracks different length, is there any reason you couldn't specify different tempos for different tracks?

If we do this, then we can have differences in note lengths that can get rather small, and can therefore have the situation where we get different track with lengths that are both pretty long and whose greatest common factor is quite small, leading to a large period for the two tracks combined.

Well specifying a different tempo is probably a lot more complex than just having different length patterns for each track. For different length patterns, the tracker still steps forward one row every beat. The cause of the pattern phasing is that the patterns reach their ends and loop at differing times. You could make a tracker that lets you specify different tempos for each track but it would definitely be more complex - effectively it would just be multiple sequencers running independently. No reason you can't do it, you just need to write a custom sound engine for the game that supports that. If that is what they did for Metroid then yes it could take a very long time indeed before it loops properly.
As you say, if you wanted that effect with streamed audio it makes more sense to play back multiple tracks at the same time.

It's just the controls we get used too.

I've played a few old games, it takes a little time to get reacquainted with the controls, but it ain't too bad.. how analog sticks changed it so much without us really noticing.. until we go back to the older games.