Parodius (Parody + Gradius) plays exactly like Gradius - you pick up capsules that advance your power meter bar, where you can choose whatever upgrades you wish. Also stealing from Konami's other popular shooter, Twinbee, you can shoot clouds and pick up a variety of colored bells, which give you even crazier power-ups, like quadrupling your size or exploding a nuclear bomb. When you die, you're sent back to a checkpoint, so there's a lot of the same memorization.
The graphics are noteworthy for their overt brightness, but it's really the sound design that takes the spotlight. Using the Looney Tunes philosophy that classical music is funny, much of the songs are directly based off of real music, and given a wacky spin. You have to admire any game which includes boss battle themes based off of "The Bumblebee Song" and "The Can Can". It's all gloriously ridiculous.
There are 2 versions of this game available. The Japanese translated version and the PAL version. The PAL version has music that is slightly faster than normal. This is from the PAL to NTSC conversion.