Indie studio On The Fly Entertainment has launched its debut project for the Xbox Live Indie Games service, mixing a gameplay concept introduced in the freeware puzzler Blocksum with battle mechanics from Nintendo's Puzzle League series.

Sum Fighter pits high school students and faculty against one another in a series of math-based puzzle battles. Numbered pieces on the playfield become larger in shape and in numeric value when linked with adjacent blocks. Players clear these pieces and earn attack points when like-numbered blocks connect; two "2" pieces will disappear after being linked, as will three "3" pieces, and so on.

The play mechanics are difficult to grasp at first -- especially if, like me, you're a Puzzle League fiend and are confused and frightened by all things math -- but the game's head-to-head setup is solid, and the art style helps to sell the experience. Sum Fighter is priced at 240 Microsoft points.