DE・JA is a remake of the computer game of the same name, a Japanese style detective/mystery adventure with adult scenes.
The remake features higher-quality graphics; some locations/characters were re-drawn from scratch, sometimes to the point of looking differently from the original design. Voice acting was added to the dialogues. Some cutscenes were added, or altered by including animated sequences.
Text and gameplay remain largely the same. The verb commands are now represented by graphical icons, but object sub-menus look exactly the same as in the original version, and generally the gameplay progression hasn't been changed.
Scenes with adult content have been removed from this remake, though the abundance of sexual innuendos in the dialogue and even gameplay mechanics ("Touch" command etc.) are still there.