My yearly nominate for Labor of Love!

+ Insane replayability
+ Insane character customization
+ Feeling of constant progression
+ Interesting lore and atmosphere
+ constant updates and bug-fixes. Even after years this game gets love from it's one-man game-creator. This keeps me coming back.
+ "Just one more dungeon"-feel
+ even my girlfriend watches me play sometime.

- you will get addicted and neglect other things. Sleep will be your first neglection.
- while addicted this game will haunt you in your dreams, leading to very bad sleep.

~ It is highly recommended to take a look at mods, although several may brake the fun or brake the game altogether, you have been warned!
~ if you have performance issues (which at later levels with massive spawns and effects might happen): there are several mods that fix this!
~ remember that mods need to be installed before starting a new char!

Final verdict:
This is THE GAME for in-depth character-creation nerds, like myself! Basically the whole fun and all the hours of this is char creation and planning before starting a new go. Another batch of hours is trying to get (really fun and special) achievements with special hardcore builds, if you are into that! (you probably are, if you are into building chars)!

ENJOY!!!!!!!!!!!!!!!!!!!!