Thanks for playing the game and for your valuable comments!
I'll look to see if I can make the comet hit more obvious. There's an explosion effect at later levels of the comet, but I might add a smaller "boom" thing for the earlier levels for it's more obvious, thanks for the feedback!
The coins are meant for purchasing player buffs in between games, sounds like I should make it more obvious!
Regarding the skills, I've given some thought into a sort of "skill preview" of sorts, but it's a lot of work, so I'm still on the fence about it. The intention is to have each skill (at the same level) be roughly equivalent in terms of dps, but I haven't really balanced the skills yet.