Successfully complete the indicated task to unlock the corresponding stamp:

Dig Dug
  Carrot: Grab the Carrot. 
  Complete Dig: Successfully dig the entire level. 
  Cucumber: Grab the Cucumber. 
  Eggplant: Grab the Eggplant. 
  Green Pepper: Grab the Green Pepper. 
  Mushroom: Grab the Mushroom. 
  No Dig: Successfully complete the level without digging. 
  Pineapple: Grab the Pineapple. 
  Quad Squash: Successfully squash 4 enemies with one rock. 
  Tomato: Grab the Tomato. 
  Turnip: Grab the Turnip. 
  Watermelon: Grab the Watermelon. 

Galaga
  Blue Spaceship: Destroy the Blue Spaceship. 
  Boss Alien: Destroy the Boss Alien. 
  Destroy Fighter: Successfully destroy your captured ship. 
  Dragonfly: Destroy the Dragonfly. 
  Dual Fighter: Successfully destroy the enemy holding your ship captive. 
  Maple: Destroy the Maple. 
  Perfect: Win a perfect game in the Challenging Stage. 
  Scorpion: Destroy the Scorpion. 
  Stage 10: Reach Stage 10. 
  Stage 20: Reach Stage 20. 
  Stage 30: Reach Stage 30. 
  Stingray: Destroy the Stingray. 

Pac-Man
  1600: Eat all the ghost after eating a single Power Pellet. 
  1600X2: Do the above task twice in one round. 
  Apple: Eat the Apple that appears in Round 5 or 6. 
  Bell: Eat the Bell that appears in Round 11 or 12. 
  Big Eater: Successfully complete Round 21. 
  Cherry: Eat the Cherry that appears in Round 1. 
  Galboss: Eat the Galboss that appears in Round 9 or 10. 
  Intermediate: Successfully complete Round 5. 
  Key: Eat the Key that appears after Round 13. 
  Melon: Eat the Melon that appears in Round 7 or 8. 
  Orange: Eat the Orange that appears in Round 3 or 4. 
  Strawberry: Eat the Strawberry that appears in Round 2. 

Xevious Resurrection
  100 Items: Collect 100 shield items. 
  4 At Once: Successfully destroy 4 ground enemies with one bomb. 
  All Clear: Destroyed the Final Boss. 
  Boss 12 Clear: Destroyed the Level 12 Boss. 
  Boss 9 Clear: Destroyed the Level 9 Boss. 
  Enemy Collector: Successfully shot or bombed all enemies. 
  Free Play: Play Xevious Resurrection 50 times. 
  Laser Cancel 100: Used your shields against lasers 100 times. 
  No Shield Clear: Successfully clear a level without using your shields. 
  No Weapon Clear: Successfully clear a level without shooting and bombing. 
  Sol Discovered: Successfully found the hidden Sol Citadel. 
  SP Flag Found: Successfully found the hidden SP Flag.