Genetos is tres cool. It's a little dojin shmup in four levels, but each level corresponds to an evolution in the genre of the shmup, and your ship's powers change and increase as you "evolve."
That is, the first game level is Space Invaders, and at the end of it you 'evolve' the ability to move in two dimenions rather than along a line. The second level is an 80s shmup, with waves of attackers in predictable patterns. The third level adds bombs, more firepower, and hoards of enemies -- and the fourth level brings us to bullet-hell.
It's enjoyable in its own right, but also interesting as a "game about games." That is, it reminds me, in a way, of Understanding Comics, a comic book about comics; this is the first thing I've seen that works in a similar way for games, albeit within the restrictive form of the shmup.
I am also relieved that even I, who notoriously suck, can play it, at least with the difficulty cranked down low; after all, if the purpose is to impart something about the history of the genre, why exclude even llamas from experiencing it?
It does crank up considerably harder for those who are serious about their shmups, however.