Wolfenstein 3D clone? I think not. This is what Wolfenstein 3D should have been.
The story is nothing groundbreaking: You are an agent working for the british secret services who discovers a plot to take over the world. His mission is to take out Dr Goldfire, an evil scientist leader of the S.T.A.R. With the help of some aliens and soldiers, Goldfire is causing considerable trouble so he has to be eliminated. So I guess the storyline gives more than a reason to start shooting (almost) everything that moves.
In order to best describe this game I think it should be fair to compare almost every aspect of it to Wolfenstein 3D. First, the engine was enhanced in order to allow some new features to be added. The status bar is much more user-friendly: It tells you what's going on, for example if a door is locked it tells you what key you need in order to unlock it (and considering there are 6 keys in the game this is rather useful). There is also an auto map which makes it easier to navigate the levels, and we all know wolfenstein 3d engine games tend to have some maze-like levels which often manage to be annoying. This is not the case here but even if you run into a maze or you simply get lost, the automap will easily allow you to find your way back.
One of the most interesting features added is the fact that not everything that moves wants to kill you. Aside from aliens, robots, security guards, troopers and so on, there are also some scientists that may be friendly and help out the player, for example by giving him information on the base etc. Generally one must try to keep these scientists alive as their survival allows you to get more points at the end of a level. When you talk with scientists however, some of them might actually be working for Goldfire and they might try to kill you as well. Another interesting feature is the Food Tokens. In the levels there are Food Units that will allow you to restore your health if you have food tokens. This is a nice addition to the already well known medikits.
But what makes Blake Stone better than Wolfenstein 3D are the good level design, and the large number of different types of enemies that you are going to face. Wolfenstein 3D had 3-4 types of enemies that you encountered all the time through the levels, but here it is different: There are many different types of monsters and aliens and all of them behave differently. There are normal types of aliens that just throw acid balls at you, or aliens that can go into a water form and you can mistake them for a pool, various types of robots and other strange aliens that can also be regenerated by a certain item in the map. There are also various hazards and obstacles, such as electric barriers that must be deactivated using switches and other things. Wolfenstein 3D had none of this. I can understand that Wolf3d is indeed older but since this game runs under the same engine, I'm sure ID Software could have made Wolf3D much better than it was when it was released.
The other thing that makes this game good is the level design. There is a high number of textures to make the game as less boring as possible in the first place, and the levels don't look all the same like in Wolfenstein 3D. Some of them are also pretty big and it takes some time to explore them, but due to the variety of monsters and places they're never going to become boring.
The game is divided in 6 episodes like the original Wolfenstein 3D. Each episode has a different theme and difficulty, as well as a different final boss. In order to move through the levels you need to use an elevator like in Wolfenstein 3D. However this elevator is unique: You can go back to the floors you already visited (although this is not that useful) and in order to move to the next floor, you must find a red key somewhere in the current floor, then going back to the elevator. This is a nice touch especially because of how the levels are constructed, for example some use doors that can only be opened from one side and not from the other, and other things like that.
So yeah in the end this game is lots of fun and the sequel, Planet Strike, is even better. If you are a wolfenstein 3D fan you definitively need to grab this, and even if you didn't like Wolfenstein 3D, it was probably because of how poorly it was constructed (a pity because the concept was great) so I suggest you give this game a try anyways.