Prodigy Math is set in a vibrant fantasy world where players have to solve quests and battle (mostly cute) monsters, solving Math problems to do so. It is completely free. There is a lot of variation in terms of different worlds, collectable items, etc. which makes it very motivating to play.
Age and difficulty: There are battles but they are not graphic, and characters are generally cute (some monsters may look a little scary for very young players). The Math activities start at grade 1 level, but with parental guidance, children as young as age 4 can enjoy the games. The initial Math exercises require only basic counting and recognising numbers from 0 to 10.