4 is an interesting little game. John W. Wells described it well; it is a puzzle game built around a clever cursor engine. The game kept me amused for a while, is pretty much bug-free, and it looks decent.
However, that is about all the praise that I can give this game. The only thing that kept me playing was curiosity about how the game would end up. There is a story, but it is very vague, and it seemed hastily typed. The gameplay is standard; you win the game by trying every object with every other object. This can get tiresome and even frustrating. Some things just made me wonder; for example, why is there only one thing - a fish - in the spring? Shouldn't there be at least two objects in every scene to justify the cursor engine that is used to select them?
4 is an neat little demonstration of an innovative engine, but it doesn't have much replay value. It is not a complete piece of junk and is certainly worth a look, but it isn't that good as a game.
4, the point-and-click ZZT adventure game, is a well-programmed game. The engine is innovative, workable, and fairly smooth.
The rest of the game is an excuse to use the engine. The plot is nearly nonexistent, the puzzles are weak, the characters aren't, and the writing is a no-show. This is ZZT's first Myst-clone, right down to the first-person viewpoint; superficially, it looks good, but there isn't much underneath.
Now, a better game that made use of this engine would be something to look forward to...