DOR consists of four very short visual novels. Each has up to three different endings.
At first, the story tells about a door made by the devil. But this is no ordinary door: once you step through it, you will find yourself in another reality. After this explanation, the devil herself [a rather cute girl] appears and offers you free passage into three possible different realities:
1.) Kanako's Depression
A girl whom you have never met before visits you. This girl asks you for a special favor; hence it is only fair that you receive a favor in return as well.
2.) The Telephone Scandal
You, Takeshi, are still in school and want to find a girlfriend; so desperate, that you call a telephone dating service. This service gives you two choices: Meet a girl your age, or meet a slightly older woman working in an office. Both choices hold their own small surprises...
In fact, after this decision, the whole story branches into two entirely different directions. Thus, I counted these two branches as two different novels when I talked about four novels before.
3.) Armored Fighter Gyleban
In a reality far removed from ours, you, as Ryosei Motosu, are capable of morphing into the "Armored Fighter Gyleban" anytime he (or the world, whatever come first) encounters danger and fights against the evil plans of an obscure organization belonging to the even more obscure and evil Gill Grauber. His only support is his assistant Ikumi, unfortunately captured by Gill Grauberís henchman, the war goddess Maya. You must find a way to continue your battle for good (or yourself, whatever comes first) in an unusual showdown.
The BGM consists of some MIDI-themes. Most of the time, the game doesn't even play a BGM. Since the DOR-series is very old, it has no voice-acting either. Instead, sometimes nice sound effects that add a aural experience to some actions that take place. (for example: knocking at a door)
Graphics and Animation:
The graphics have not been touched-up for the re-release; they are at the same resolution as they were on the NEC PC-98, and seem to be only 16 colors too. There are no animations, but there is scrolling for graphics bigger than the screen.
Furthermore, some characters have animated facial parts. (i.e. moving eyebrows, blinking eyes, moving lips when a character is talking.) Quite a shame that there is no matching voice-acting.
The Menu that opens the paths into the different realities allows also access to a gallery of four different series of pictures, each related to one of the short novels.
My personal opinion:
First of all, I have to admit, the DOR-series (consisting of three parts) was originally quite successful, but that was several years (decades?) ago. On the NEC-PC98 with its limited capabilities (compared to PC's nowadays), they were quite entertaining. But even at that time, they were not top notch, since even then there were the original versions of "Eve Burst Error" and "Desire" from C's.
It remains a mystery to me why G-Collections had to add this title to its debut-lineup. "Chain", "Kana" and "Kango Shicyauzo", three other state-of-the-art titles; and beside them, this piece from a museum that can only be interesting to software-archeologists. Not only that, but the characters of "DOR" have no real character development. You barely even learn their names. In fact, I have just played through DOR again for this review. It took me about three hours, and I already forgot the name of the main character in the second story. Even the characters of "Kango Shicyauzo", who could be considered shallower since they are all just part of an entertaining nurse-soap, are as deep as the pacific ocean when compared to the DOR-characters.
However, while the first two stories are nothing spectacular (even Kanako tells her secret, that is hinted on the cover text of the box, right in the beginning and spoils the only interesting part of this story with it), the third story is at least a nice parody on the mecha-and-battlesuit-genre that was at least enjoyable to me.
In short, any bishoujo hall-of-shame that does not contain this title, is not complete. For anyone who doesn't want to build up such a hall, avoiding this game is a good idea. It's easy to find many better bishoujo games, but right now only "Viper Limited Edition" fares even worse.