the 80s/early 90s
About the DLC, at least I'll finally be able to get rid of those leftover points
Also, for those that care about such things, I compiled a list of the in game achievements.
WALTZ: Clear the game in 120 minutes or less.
TANGO: Clear the game in 90 minutes or less.
JITTERBUG: Clear the game in 60 minutes or less
BUST A MOVE: Don't miss with the mega buster and clear the game
HEADBANGING: Defeat a boss without your helmet
BUNNY HOP: Clear any stage jumping 50 times or less
MR. TRIGGER HAPPY: Clear the game with more than 500 Mega Buster shots
DOUBLE TROUBLE: Visit all stages twice and clear the game
MR. PERFECT: Clear the game without getting damaged
INVINCIBLE: Clear the game without dying
ALMOST INVINCIBLE: Clear the game without continuing
NO COFFEE BREAK: Clear the game without using any energy tanks or mystery tanks
AIR SHOES: Clear the game without falling into any holes
MEGA DIET: Clear the game without picking up more than 8 energy pellets
ENCORE: Clear 4 stages using the same special weapon
PEACEKEEPER: Clear the game by defeating the fewest number of enemies possible
CONSERVATIONIST: Clear the game by using the least amount of weapon energy possible
FAREWELL TO ARMS: Clear 4 stages without using any special weapon
GAMERS DAY: Clear the game 5 times in 1 day
DAILY DOSE: Clear the game once a day for 3 days
WHOMP WILY: Clear the game once
TRULY ADDICTED!: Clear the game for the 10th time
TRULY HARDCORE!: Clear the game for the 30th time
CONQUEROR: Defeat your 100th enemy
VANQUISHER: Defeat your 500th enemy
DESTROYER: Defeat your 1000th enemy
WORLD WARRIOR: Defeat every type of enemy
TRUSTY SIDEARM: Defeat the 8 bosses with the mega buster
PACK RAT: Collect 999 screws
VALUED CUSTOMER: Purchase all items
SHOP A HOLIC: Purchase 30 items or more
LAST MAN STANDING: Defeat all bosses with only one pixel of energy left
SURVIVOR: Defeat one boss with only one pixel of energy left
HARD ROCK: Reach a boss' room without getting damaged
HEAVY METAL: Reach a boss' room without shooting
SPEED METAL: Reach a boss' room without stopping once
FANTASTIC 9: Accumulate 9 lives
FULLY UNLOADED: Hit a boss with all special weapons before destroying it
BLUE BOMBER: Defeat a boss without getting damaged
ECO FIGHTER: Defeat a boss with only the mega buster
MARATHON FIGHT: Fight a boss for 10 minutes
QUICK DRAW G: Defeat Galaxy Man in 10 seconds or less
QUICK DRAW C: Defeat Concrete Man in 10 seconds or less
QUICK DRAW S: Defeat Splash Woman in 10 seconds or less
QUICK DRAW H: Defeat Hornet Man in 10 seconds or less
QUICK DRAW J: Defeat Jewel Man in 10 seconds or less
QUICK DRAW P: Defeat Plug Man in 10 seconds or less
QUICK DRAW T: Defeat Tornado Man in 10 seconds or less
QUICK DRAW M: Defeat Magma Man in 10 seconds or less
QUICK DRAW X: Defeat the final boss in 180 seconds or less