The beta of Rumble Fighter has ended and the servers are down, so it's not currently playable. It was pretty fun, but it's a little childish in the way that's it's drawn - much like Albatross, which I used to play as well. I've experienced most aspects of the game, and although there's not a whole lot to the game, I can say it's more than deserving of at least a look. Definitely not for everyone.

Granado Espada is also free, as far as I know.
My brother tried it out during a beta session and said it was pretty terrific, so it's definitely worth a check.
http://www.granadoespada.sg/en/