Dungeon Keeper Gold
When I have seen that KeeperFX (a custom engine to play the game in higher resolutions) reached the version 1.0, so with the "stable" state, I started again to play the game.
Turned out to be awesome !
It can not only be used to play the original campaign and extra levels in FULL-HD (and more), it also contains a lot of other fun made campaigns and levels !!
Now this game really stand the test of time !!
Not only it's good as a Dungeon simulator, with lively creatures that do their stuff in autonomy, but the possibility to use creatures in first person view opens up a lot of new game types, from DOOM-like where you must just win a dungeon with a single creature, from puzzle-like games, where you need to select the correct creature for every job, etc...
I tried different "similar" games before, in the hope to find the perfect modern substitute, but none had the right recipe...
Some examples:
Dungeon Keeper 2
Was made more simple and more cinematic, removing a lot of interactions, with less interactions between creatures too, these last ones also have less personality, they does everything happily... also the first person view while inside creatures is grafically dumbed down, there are no more creatures with a distorted view (like smoked view, exagonal view, stretched view, etc...) but just a different color view...
The Reaper is part of the "made more simple" gameplay, now you don't have anymore to deal with its difficult character, you just summon it and wait while it kills your enemies.
War of the Overworld
Very well made game, with the same feel, but still less (or not existent) interactions between creatures... also no first person view... it missed a lot of opportunities...
Dungeons 2 and 3
Same concept, a little different feel, interactions between creatures are really minimal... it introduces the possibility to attack the overworld, but there it becomes a "normal" RTS, where the creatures becomes soulless soldiers that blindly follows orders... also no first person view..