I know this is not a game, but I want you to sing this every day!

http://studyjams.scholastic.com/studyjams/jams/math/multiplication-division/divisibility-rules.htm

Advanced game with factor trees:

http://www.mathgoodies.com/factors/prime_factors.html

Advanced game adding fractions with unlike denominators:

http://mrnussbaum.com/tonyfraction

Advanced game for adding fractions with unlike denominators:

http://www.math-play.com/football-math-adding-fractions/football-math-adding-fractions.html

Advanced game using all types of fractions and more:

http://mrnussbaum.com/castle

Advanced game converting improper to mixes fractions:

http://mrnussbaum.com/clarafraction

Advanced game adding fractions with unlike denominators:

http://www.mathcats.com/explore/oldegyptianfractions.html

Fairly easy factor game:

http://illuminations.nctm.org/ActivityDetail.aspx?ID=12

Fairly easy greatest common factor game:

http://www.fun4thebrain.com/beyondfacts/gcfsketch.html

Fairly easy greatest common factor game:

http://www.oswego.org/ocsd-web/match/dragflip.asp?filename=slanegcf

Fairly easy least common denominator game:

http://www.sheppardsoftware.com/mathgames/fractions/LeastCommonDenomimator.htm

Easier faction game to add 2 fractions to make a whole called Fractone:

http://www.coolmath-games.com/0-fractone/index.html

Simplify fractions with baseball:

http://www.math-play.com/baseball-math-simplifying-fractions/simplifying-fractions-game.html

Easy fraction game using models:

http://www.interactivestuff.org/sums4fun/shade.html

Easy prime and composite numbers game:

http://www.math-play.com/Prime/prime-and-composite-numbers.html

Easy prime and composite numbers game:

http://www.sheppardsoftware.com/mathgames/numbers/fruit_shoot_prime.htm