If you have never heard of Mr.Nussbaum.com you should scroll on over and check it out! He has some AWESOME math games but I would suggest filtering them and not just letting the kids choose their own.
There is one game where you kill buffalo with math facts on them with arrows and another where you compare numbers and beat up famous geniuses, like Einstein and Bill Gates. I had issues with these, but you might not!
My plan is to pull some of these up on days that I do math centers to add a little variety to our instruction and review concepts that were taught earlier in the year in an engaging way!
This one is cute, War Pretzels for addition and subtraction facts. You get to select the pretzel that is going to be your player and then you arm wrestle another pretzel. You have to continue to answer problems correctly to stay in the match!
The Cash Out game has students making change for animals who have bought different things in a grocery store. It is great. They are basically practicing counting money but there is a time clock. They try to see how many animals they can make change for before the clock runs out. (My best was 35, hehe!)
My last suggestion would be difficult for the average Second Grade jelly bean but it is SUPER cute! In Maximum Capacity you must get these monkeys to a party by putting them on the elevator. The goal is to get as many monkeys in without going over capacity.