Number Builder is an single screen educational platformer to help you improve your maths over twelve levels. You play the role of a builder who must move around a building site, climbing ladders, looking for sums to make a target number. You are given a starting number and you must pick up sums to add or subtract from that number to make the target number. Each level is split into three different target numbers and each must be completed before a bucket is lifted to the top of the screen. Once a level is completed you get paid money before attempting the next level.

Before you play the game you can select your starting level as well as your builder who vary in different speeds. There is also a Self Test where you choose a level of difficulty and attempt to give the correct answers to ten sums before receiving a score.