Mythus
I won't pass any judgement on the game, but we did play it for about six months when it came out. Our "JourneyMaster" even managed to pick up the Bestiary from GDW by mail. Honestly, if it weren't for him, none us would have been able to understand how to play our characters.
However, that said:
If you can find the game, it has miles and miles of interesting ideas that would fit the flavor of any 1st edition game. There are plenty of extras we probably would have seen in the later books of 1st edition. For example, a HUGE table for gems and minerals and the effects they could have when used magically, ditto on herbs for herbology (one of the many "magic-producing" skills).
The "MagicK" system has its own 2nd book. It's based on levels and magic points. It reminds me more of the incremental style systems of OAD&D than the descriptive? ones in WoD and Ars Magicka. I think it's trying to be both. You're character will most likely use magic, know hundreds of spells that are often similar, and gain hundreds of "Heka" points to spend based off of skills (mostly).
At it's heart the game had a single mechanic to deal with die rolls called a DR - difficulty rating. It scaled like D20, but was percentile-based and involved multiplication or division, so it may not have been to everyone's tastes.
However, it also has miles and miles of rarely edited text just like 1st edition. I'd say the formatting is somewhat better, but the sheer size and number of all the skills (over 200 if you count subskills) and specialty rules is off-putting. If this could have come out like 2nd Ed. with more support and split up into splat books with larger fonts, (and better editing) I predict that it would have done better than 2AD&D, but not 3rd. (IMHO)
The game does have a some mechanical problems, as well. Distances are a pain. Not only tough to find, but based off of old-world lengths such as "rod" and "chain". The sheer number of everything (classes, skills, spells) is overwhelming for even the most diehard players. And the text is riddled with archaic word choices. Magic=Heka, Wizards=Dweomercraefters, Skills=Apotropaism, as well as Buffoonery, Clothwork, Domestic Arts & Sciences, even Musical Composition (separate from Poetry/Lyrics).
I agree with both Henry about the rules and with Thalmin about the density of the text. The flavor of the magic system is were the archaic rules really shine. Things "feel" like old school magic. Pentacles, magic boosting via pacts with demons, the "Laws of Magick", and the most intricate, drawn-out, magic creation system you will ever find. In my mind, this is what 3rd Ed. would look like if they had done a point-buy system for spell and magic item creation.
If you like Gygax's writing style , organically created rule systems, and world-building, this is a must have. It's what he was essentially working on from 1985 - 91.
Okay, so ignore the first 5-6 words of this post. I enjoy the books, but will no longer play the game. If you are a diehard 1st Ed. player, you will find something here for you. If you really like Necropolis, chances are you'll like the world setting, too. If you plan on playing the game, I'd suggest against it. So many things are really nice, like 15 magic systems, that aren't portable. But the amount of memorization is just too much.
When I originally got these books (still have 1+2+Necropolis) I devoured them. Now they sit in the closet. If you have any specific questions I'd be happy to answer them. (so I'll stop writing my own little novel

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PS: JohnSemlak, if you are looking to broad your mind with non-D&D fantasy RPG's, I'd suggest another route.