Caesar 3 is a game I've probably put thousands of hours into over the past 15 years or so. It's always been a game that's easy to pick up and is a game that I've always turned to in moments where I don't really feel like playing anything else at the moment. The game has a bit of a learning curve, but isn't terribly obnoxious. Basically, it's easy to learn but hard to master especially with its confusing AI pathfinding.
I recently played through all the Broken Sword games again, in order so I could prepare myself for the fifth installment of the series. In order to do this, I forced myself to finish this crap pile. In doing so, I wasted about 15 hours of my life. Bland, lifeless level design with too many browns, tans and blacks filling the color palette on most maps - gone are the vibrant colors and beautifully drawn landscapes from the earlier games (even Sleeping Dragon's design was pretty good). Voice acting that sounded like the actors were bored (except for Rolf Saxon's George Stobbart, of course). Not to mention Nico, a MAJOR character, was given a role that seemed mostly like a glorified cameo. I could go on, but GOG has a character limit. I'll just say that there is absolutely no reason to play this game before playing the Serpent's Curse and you should avoid at all costs.
A quintessential adventure game that everyone who is a fan of the genre should play - it's pretty much required playing in my opinion. The game's characters and depth really get you sucked in though some of the puzzles are pull-you-hair-out nonsense that will most likely require you to refer to a walkthrough. The art design, music and voice acting are all top notch and when you finish, you'll definitely want more...which you can find in the game's sequel: Dreamfall. Highly recommended.
Quite possibly the greatest RPG ever made. Why? The dedicated multiplayer community. This was one of the games that defined my teenage years and every now and then I'll come back to it to get into some good role play on one of the fan-made servers that can sometimes last hours on end. Unlike the many disappointing MMO's out there, the thing that NWN does right with multiplayer is allow its player base to create their own private servers with whatever content they can think up. Different servers will sometimes have their own ".hak packs" which consist of custom content made by either the server's creators or other players in the community. These can include custom music, ambient sounds, skins, textures and so on.
