The flavor text, along with the actions described, clue that this is a ripoff of Super Mario Bros 3. The things are various entities that appear in Super Mario Bros 3. The legend may be missing pictures, but when deduced, it turns out as shown below:

We can at the same time figure out the names of the entities depicted in the diagram. Using the flavor text, we know to take the name used in Super Mario Bros 3, even if the entity was later renamed.

  1. Spiny
  2. Super Mushroom
  3. (Green) Koopa Shell
  4. Coin
  5. (Green) Koopa Troopa
  6. Fire Bro
  7. Bullet Bill
  8. (Red) Koopa Shell
  9. Turtle Cannon
  10. Switch Block
  11. Piranha Plant
  12. Goomba
  13. Brick Block
  14. Lakitu
  15. Bloober
  16. Venus Fire Trap
  17. (Red) Koopa Troopa

We use the indexing chart to index into the appropriate word in each entity name, giving SPACE-FILLING CURVE.