I remember Parasite EX. The creator, DSG, was kind of an asshole.
Agreed. I liked the original Parasite, and Parasite 2 had potential, but DSG had his head too far up his own ass to make a game that people wanted, and would rather add in whatever idea popped into his head before fixing widely known game breaking bugs that had been in the map since its early versions. A creator of anything who flat out denies anyone's help/ideas on a map and bans anyone with a difference of opinion (yes, I was banned from his forums quite a few times) has no reason to even have a forum based around his game. I recently came across someone who is apparently taking it upon themselves to make a Parasite 3 (Parasite Revolution/Resurrection/something) and they seemed nice enough, but I haven't seen any games up lately. I have liked the "whodunit" genre since Starcraft, where "The Thing" was a huge UMS map back in the day, and Parasite is no exception. Metastasis seems more based around shinies than actual gameplay (especially with the UI being swapped out, which can cause problems if you go into another game without restarting WC3), but last time I played of it was an early version (and I hate maps that put more emphasis on graphics than gameplay; likely why I play Dwarf Fortress so much)
Dark Ages of Warcraft is great if you like a RP-ish/lore heavy RTS game. It's a huge map based on the events after Warcraft 3's campaign (about where World of Warcraft picked up) with each player taking control of a unique nation, usually with different branches of their tech trees. Night Elves, for example, can kill Azgalor in Felwood to regain control of the World Tree and get some new units; if the World Tree is destroyed they lose their druidic powers, and if they want they can go "evil" and have a completely different unit set.
Vampirism Beast is another good, often hosted, relatively balanced game. It pits 10 humans against 2 Vampires, and it's the humans job to build a base and outlast the Vampires as they try to slaughter everyone. Both humans and Vampires get access to bigger, badder weapons as time goes on and it ends when the Humans can build up their slayers (hero units) up enough to kill both Vampires or the Vampires kill all the humans.