A tracking quest that has students master subtraction facts from -1 to -12. You provide your own papers, but students must solve 60 problems in three minutes. This is 3 seconds a problem, which is the benchmark for 4th grade in my district. As students submit completed papers, you check them off in the quest, opening the next task/level. It does state in the story that a classroom dollar is given for each completed level, but you can erase that.