+=3

This game makes a point about interactive fiction design. It makes it well and quickly (one you have figured out the solution, probably by reading the source or the walkthrough). So, although this game is not enjoyable as such, it does the one thing that it attempts to do quite well.

What is the point that it makes? According to Karl Muckenhoupt, the point is that "it is possible for a puzzle to have a completely logical solution, and yet be nearly impossible to solve except by randomly guessing commands". Without disagreeing with that, I would say that the point of +=3 is that "conventions of play are there for a reason". Either way, it's a good point, and +=3 is a name that you might want to drop in a discussion now and then.