...achievements would be kinda cool, ya know? You don't HAVE to do them in order to play the game, but they're fun to collect for the ones who like them. Here's some for the original episodes:

Where's the Any Key? Don't skip the intro cinematic.
Mother in Wall Elevate the Queen into the ceiling
Vegetarian Finish "Tossed Salad" and "Carrot Juice"
Loose Screws Defeat Devan's Robot boss
Verminator Finish "Weirder Science" and "Loose Screws"
You kiss your mother with that mouth? Eat a carrot in the sewers of "Victorian Secret"
Street Urchin Finish "Victorian Secret" and "Colonial Chaos"
No Smoking Walk into a smoke ring
Trippin' Finish "Purple Haze Maze" and "Funky Grooveathon"
Wet Behind The Ears Jump into the water in "Beach Bunny Bingo"
It has crabs, LOADS of crabs Defeat Uterus Boss
Tanned Finish "Beach Bunny Bingo" and "Marinated Rabbit"
Sparkle Sparkle Finish "A Diamondus Forever" and "Fourteen Carrot"
Zapped Finish "Electric Boogaloo" and "Voltage Village"
King of my Castle Defeat the Bolly boss
Oldschool Finish "Medieval Kineval" and "Hare Scare"
Swinger Finish "Thriller Gorilla" and "Jungle Jump"
Firefighter Defeat the Bubba boss
El Fuego y el Hièlo Finish "A Cold Day In Heck" and "Rabbit Roast"
Star Power Destroy the entire Star Block cluster in "Bad Pitt"
But wait! There's more! Allow Devan to transform completely (because we all know you can kill him easily DURING the transformation).
Ressurection Finish "Burning Biscuits" and "Bad Pitt"
Back to 1990 Enter your name in the highscore list
Sharing is good Finish the Shareware levels
Chef Create and play a homecooked level

...Just some I came up with. Whatever, this won't be implemented but it's fun to dream on. :P