Orbital all the way. It was well worth the $2.99 for it so you should definitely pick it up for $0.99. Admittedly I haven't played Gravulous.
I have both, and Orbital is WAY better. Gravulous takes way too long to shoot, as the planets take ages to completely stop, then slowly grow. Orbital is much faster. Oh, and I love neon vector graphics.
Thanks Bat, I got orbital based on your recommendation the other day and I absolutely love it! Reminds me of DX ball for some reason. I know they're nothing alike, but the quickplay and explosions and music all remind me of dx ball.
While it's $0.99, Orbital is WAY better. At $3 vs $1, that's much harder... So - buy Orbital RIGHT NOW!
While I love the cracking sounds the planets make in Gravulous, Orbital looks so beautiful in action now that I've gotten to play it. Only thing I wish I could do is aim on my own, not wait until the aimer rotates to where I want it to be. But yeah, at a buck: Orbital > Gravulous