The Artifact is a classic 1995 three-level mapset. It might be one of the highest-quality 1994/1995 productions I've seen, standing alongside such releases as UAC_DEAD or Galaxia. Much like them, Artifact has something of an unique air about it... a feeling of a true adventure, where you can palpably feel the author's enthusiasm and creativity as you go, each new room and area somehow feeling unique and lovingly crafted despite the simplistic looks. One downside of the mapset is that progression is occasionally confusing (such as one door switch on map03, hidden on a column that lowers into the ground).
A set of maps, carefully tuned for pistol starts, pretty hard/challenging. The maps are rather small and have exactly one secret. There is no stylistic consistency; there are a few bases and castles, caves, hellish maps and so on, everything totally mixed up. I can assume the earlier maps have their slots because they are easier and the later maps - harder. MAP26 is probably the most difficult one. mlm12 reminds me a bit of Going Down, as the levels are small, packed with enemies, and one different from the other. But mind, they are less polished than GD. Some maps have a pretty high 2000's level of detail (the ending corridor from MAP09), some others are much more basic looking (MAP02). IMO they are rather good looking (above average).
Bugs/problems: The mapper leaves all the doortracks without "lower unpegged" flag, so they move with the door, I'm sure he knew how to prevent it but he preferred the doors to behave this way. What is more problematic for me: unreliable W1 monster teleports, places where you can get stuck and decorations impeding player's movement, no Boom actions but some maps require -complevel 9 due to traps not working with limit-removing compatibility.
Favourite maps: 03,08,17,24,25,26. I would definitely recommend giving it a try: the maps are so different everyone will surely find something that appeal to them.
Finally played this one today, pretty good for an old-school level, hub layout, so not so linear, varied locations (including a huge canyon area and an underground cavern), LOADS of monster traps triggered by linedefs, including traps WITHIN traps (very nice). Not too much of a challenge, but quite fun.
Good atmosphere, but ruined by the terrible gameplay. Tons of identical enemies attacking you over and over, plus some very dark levels where it's impossible to see where you're going, all amount to a mod more annoying than scary.