The game runs well as an endless runner, but the fireball seems a little unnecessary with its current implementation. Focusing on both the dragosaur and moving the fireball around is a bit tough, so I normally just moved my mouse to sit in front of it so It would hit something no matter when it was fired. And I couldn't keep it out of the way until I wanted to use it because if a second fireball was fired while I was waiting, they would run into each other and destroy each other, making a sort of use it or lose it scenario. If it weren't a set firing time or it didn't destroy itself, it might work better, but I only really got good scores when I wasn't actively using the fireball, getting second place on the leader board with a 928(though it hasn't updated to show it yet).
The sounds are okay, I know someone already mentioned the jump sound could use some variation, but I think it might be nice to keep the music playing, as as soon as the track has ended, it doesn't loop and is gone until you refresh the page.