I'd say yes: The entry fees on the challenges range from 0.25$ to 0.75$. If you set a new highscore it seems that you get your entry fee doubled right away.
There are two kinds of win systems:
In the "Top Spread" games you must attain a win streak of X people trying and failing to beat your score to get a big price. The prices are gift cards mostly, there is one Tetris and one Asteroids challenge for 1 BTC and a Tetris Challenge for 250$ currently. In addition the top 5 in the leaderboard get paid money to their balance for every player that tries and fails to beat their score.
In the "Bonsai" games the entry fee of everyone that fails to beat the current highscore is added to the jackpot. The person to hold the Highscore at end of round (60 minutes as far as I could observe) get's the jackpot.
The games currently on the site are: Tetris, Asteroids and Simon Says.
So yes this thing is completely skill based. If you're good at playing those games you likely come out at a profit.
Edit: @OP If it is possible I suggest you change the thread title to "Win Bitcoin by playing Asteroids and Tetris". Because the current thread title might look like a scam to people knowing that Bitcoins are worth more than 0.25$ and they're likely to not even look at it. At least that was the case for me. It took me a second look at the post count to look at it, because with 10 pages of replies there must be something interesting in here.
Reason for Edit 2: corrected descriptions of the challenges.
Thanks for the awesome comment. If you set the new high score, you get your play fee credited back to you.