What happens when you take maths problems, cancer, and weird, cheesy dialogue cut scenes, then smash them together into a mobile game?

What happens is Zero\Sum. It's a strange mix of ideas that still somehow manages to be compulsive and entertaining in ways that it probably shouldn't be. Plus it's literally helping cure cancer, so you can't really complain.

Count on me

After your professor is killed by terrorists, it's up to you to try and finish her equations which, for some reason, are going to cure cancer.

These equations are the meat of the game. You need to balance them out so they add up to zero. Things start off simply, with you adding plus or minus symbols here and there to make the strings of numbers end up as nothing.

But the deeper you get into the campaign, the more is thrown at you. You'll get equations that cross like crossword puzzles, the pen that you're using will start fading, and there are some tight time limits too.

Zero Sum iOS review screenshot one of the puzzles

These additions keep things interesting, but there's still a neat, head-scratching rhythm to the game. There are eureka moments aplenty, and while it might not be the most interesting looking game in the world, the cut-scenes make up for that.

There are other modes as well, so there's always something to keep your mathematical brain interested.

And on top of all that, half of the profits from the game are going to charities that are actually fighting cancer, so you're doing something pretty good with your money for a change.

Mathletics

Even without the extra charitable bent, Zero/Sum would be worth checking out. It's a maths game that doesn't take itself too seriously, and that's a rare thing on the App Store.

If you're looking for a game that's going to train your brain, and that you're going to have fun with at the same time, you should definitely check this one out.