In Catch the Mice players are hungry cats, trying to catch colored mice – but you probably already figured that out from the title.
On a turn, a player rolls the two dice, then "catches" a mouse of the color showing on the dice, assuming the player hasn't already collected that color this turn. If you roll the same color on both dice, you steal a mouse from your opponent! You may keep rolling but if you can't catch a mouse after a die roll, you lose everything. The game ends when there are no mice left, and points are scored for captured mice.
Polar Derby features the same game play as Catch the Mice but instead of mice players collect bears on roller skates, which is completely ridiculous and unbelievable. Bears on pogo sticks, sure, but not roller skates...