I entirely agree with that point of view. Another favourite of mine that I recently remembered and looked into is Duke Nukem 3D (perhaps more accurately called Duke Nukem 2.5D because of the style of the graphics). Fantastic in its day (1996), and even now is still a good game.Tkwiget said:
For those people who like enhanced graphics, there is a Duke3D High Resolution Pack (an example of the quality can be found [ame=http://www.youtube.com/watch?v=yIELlabpKrk]in YouTube[/ame]) which looks particularly good. Since the source code for the game was officially released a few years ago, there have been many modders having a go at improving the game, some achieving great results.
Extra level maps are in abundance, and some of them are cited to be amazing (one website I found with a small collection of what the author considers to be great maps can be found here). In particular, the series of maps named "Roch" (from Roch to Roch8) are widely said to be fantastic.
Duke Nukem has a single player mode, in which you trawl three episodes battling aliens and mutants with a variety of imaginative weapons (the Freezethrower and the Shrinker, to name a couple), but if you're looking for a real challenge, why not try the multiplayer option? Go face-to-face with real people, and shoot their heads off with the faithful RPG or the devastating Devastator (the clue's in the name). What with so many high quality and detailed maps available, you're bound to find a few hundred you like, which means you'll never get bored shooting people in the same location time after time.
For those technologically adept people, try making your own maps! Build lets you create anything to want, and like most level editors isn't too taxing when you're making simple maps. You can always learn advanced features and read tutorials to improve your abilities. Build itself comes with an example map that contains every feature seen in Duke (the map is aptly named "Zoo"), so examples of sliding doors or explosive walls shouldn't be too difficult to come by. Since Build is an old program, it does have its limitations (for example, floors above floors aren't particularly supported, and there's a trick to getting them to work properly), but no matter. Many people have found ways around these limitations, and have produced amazing maps of their own for you to rampage through.
This is turning into a review now, so I'll end it here and give it 9/10. While some features seen in later games are missing (for obvious reasons), the game still does very well with what it has.