Still one of my absolute favourites
This game was amazing when it came out and I still enjoy replaying it. I had both the PC and the Playstation 1 versions of the game. The PS1 version was actually quite compromised, they took out the iMUSE system and just streamed pre-recorded versions of the PC midi music from the CD. The framerate on the PS1 was also a bit dodgy and the controls often required some quite convoluted combinations to switch weapons or run and jump.
On the subject of iMUSE, I think this was one of the last titles to use midi music. It had a fantastic score with lots of unique themes and cues (I think it was by Clint Bajakian). Sadly LucasArts moved on to chopping up bits of John Williams music for future games. While having full orchestral music was nice, I think the lack of a composer creating music specifically for each level was lost. The end credits music to Dark Forces in particular is one of my favourites.
I do remember being slightly annoyed that the longest cut-scene was the one at the end of the first level (and was included with the demo). Based on the demo you'd expect massive cut-scenes after every level but usually you'd get little more than a shot of the Mouldy Crow flying away from an explosion...
Does anyone remember the box to Dark Forces? There was a screenshot of a map to a level not in the game. As I understand it this was the original first level but it was dropped as it was considered too complicated.
A few years back some fans attempted to re-create the game using the Jedi Academy engine. I believe they re-made most of the game but there were a few levels that were never finished. Their website is here: http://darkforces.jediknight.net/
I think this is the first game to ever use a texture on a wall to display vital information (when in the vault on Coruscant). I remember wondering about that area for ages until I realised that the map on the wall was actually updating as I opened and closed doors and was meant to be used to guide you to the centre of the vault. I'd never seen anything like it before then and it really blew me away as suddenly walls could do more than just be barriers.
Dark Forces 2 Jedi Knight is also an absolute favourite of mine. I really wish LucasArts would consider making another one (and preferably not the shallow experience that was Force Unleashed)...