There is a difference between The Deep and The Deep: True Horror Edition.

The Deep is more based around the exploration and platforming aspect, there are additional levels which contain puzzles and platforming for players who enjoy a slower paced puzzle experience.

Wheras The Deep: True Horror Edition has been modified to create a true horror game, tweaks have been made and the game is snappier and possibly fustrating puzzles have been removed to give an experience which is closer to a true horror game, and is more suited for let’s Play style of recording for YouTube.

In most respects the games are very similar, neither edition is a sequel or remake.