As far as I'm aware, the only way to play Jet Boy right now is online. I'm considering asking the developer of the game on his twitter (@GamibleGames) if he had any way of supplying a downloadable version, so that internet speed isn't a factor of time. However, I want to see if there are any differing opinions.
I've been able to download games from websites before so that they're playable offline, but I'm currently out of the country. I'll look into it when I get back and post my findings if I'm able to do it.
Okay, I've attempted to do so with Jet Boy, but might've just not have been able to do it correctly.
I've been able to do it with other games on coolmath, so I'll investigate when I return in 4 days.
I've thought about it a bit more, and I've come to the conclusion that once it's loaded, Jet Boy does not require internet to function, so speed of internet should just effect the time it take for the game to initially load, not the actual speed of the game.