In a nutshell, its not worth a Newgrounds page.
Let me try to be as fair as possible.
Sorry to start so harshly but first of all, this game is a basic platformer that does not have any originality besides cheap and bugged graphics. Any smock with Flash can whip this up in half a day. The graphics are basic, the physics are terribly wrong, and obviously each block, wall and spring are copy pasted and resized making the game look cheap and worthless.
Secondly, this game was not thought-out properly. For instance; whats the point of springs and wall climbing functions if you have infinite jumps, and might I add that jumping with the space button is faster and easier then wall climbing or springing. Seriously, all wall climbing does is get in the way when your falling down a long shaft with spikes on the other side. Another pointless option is the fact that dying costs 50 points yet one coin costs 10 points. Are you just encouraging us to: Collect 20 coins on a level which equals 200 points, die so that you only earn 150, reset level and get another 200 points, die and repeat. This making incredibly unfair scoring specially on online high score boards and versing other players.
Thirdly, bug central. Theres no point in making an L shaped wall, because it seems every time i spot on all i have to do is keep jump/moving forward into the corner of the L and suddenly I become invincible for the entire level. There are several bugs like that which makes some levels irritatingly easy.
Fourthly, if you are only going to provide me with half a game I will only review you on half a game. To tell players that the game has 50 levels and level skip and bonus features and what ever else you said is completely false advertising. You have not provided us with the features you advertised, newgrounds is a free-play site. That is what is expected of all members on newgrounds, and if you create an incredibly popular and memorable game I would freely be more then happy then you watch you make a sequel and expect members to pay, it happened to Bloons Tower Defense, and as much as I don't enjoy paying for a game at least its a decent game. This however, is a piece of junk. It isn't original, and even if it was free I still wouldn't rate it above a pass of 50%.
Don't get me wrong, I promise you that out of this review I'm not rating you lower because of your Mochi Ad scheme. But since you advertised 50 levels and only allowed me to play half of that, I have no choice but to rate your game out of 5 instead of 10.
And finally, learn your mistakes, and mend them. Clearly Flea 2 is a copy pasted Flea 1 with different spikes and springs all over the place, all the bugs and physics inequalities and identical to the first flea game. So the big question is, why didn't you fix them?
So let me sum up all of these things so far: Its bursting at the seams in bugs, there are glitches, there are stupid approximations of coins which make it easy for those who know more then basic maths to use the system to get an infinite score, the game isn't original, its a terrible platformer game and physics are out of wack. Each obstacle is copy pasted and resized with a little bit of music to block out all the failure. I would not rate this game as a pass in any book Sir. Yet on top of that you still expect users to pay for such a pathetic game.
So what to rate for a game like this? I agree it is a game, and it does have music. But besides that I can't find anything else to add to the rating. I guess, for creating an actual game and putting in almost as much effort to create the game as I have put in to write this review, I will provide you with a 1/10. But since you shamelessly advertised an entire game and only allowed members to play half so that you could earn money on this trash that shouldn't have passed to begin with, I can only rate you out of 5, which leaves my total score to 0/5.
Sir, I'm sorry but, you fail epically.