While somewhat more limited than most roguelikes I've played, it also seems to be an easy roguelike for beginners to "get in to", especially considering it's tile-based graphics instead of ASCII characters, sounds, excellent music, and shortness of dungeon (no more going down 100 levels like angband).

If you haven't played this game, what rock have you been under for the past 4 years? It's now free to play, and you can go onto any server and play everything, unlike most "free to play" games. The cash shop isnt bad as all the weapons are sidegrades and there is almost nothing that's really "better" than others at everything (debate continues, however). The only downsides I can see are the stupid keys to unlock the crates that drop, and the increase in trolls/retards since it went F2P. Come play with me on TFP!

The penultimate classic game, since System Shock isn't available on here. Combination RPG and FPS, with a dark, dystopian storyline full of twists and turns. The game compensates if you try to screw up the plot (the dev team thought of a lot of things) and there are multiple ways of getting through enemies and into places. Do you blow a hole in a vent and drop in? Go in guns blazing? Stealth through? Hack the security system to unlock the back door?

Put on a trenchcoat and fight some conspiracies.
Get experience and level up abilities.
Will you pick rifles? Or computers?