Rick Rocket is a little, unassuming shareware shmup -- by which I mean that it's nothing strikingly novel, but nicely polished and good fun.
The demo contains 8 levels (out of 48 in toto), and the developers have made an effort to provide a different challenge with each level. Thus, the first level involves shooting up rocks, Asteroids-style; others involve battling aliens; and one requires you to jet out from a mothership, find injured friendly ships, and tow them back to the mothership, while evading frequent asteroids. There are boss battles, quite a variety of power-ups, and the ability to replay levels to heighten your score. Comic book-style panels provide narrative continuity between levels.
I basically suck at shmups, but was able to play this fairly easily at the low difficulty setting; this does imply that even at the hard setting, serious shmuppers won't find Rick Rocket much of a challenge, however. And the graphics are straightforward sprites, so it doesn't have the strange physical beauty of a Minteresque shmup. Thus, as I've said, it's unassuming, but a pleasant enough little game.