How to Make Bad Video Games Good

Big Rigs: Over the Road Racing
>implying Big Rigs isn't a masterpiece
 * Remove the glitches and stuff.
 * Make Nightride work right.

Looney Tunes Acme Arnesal

 * Don't put in the Looney Tunes.

Dead or Alive 4/5

 * Stop the Dead or Alive series after 3

Intellivision Lives!
Other than that, this game can't be improved. Intellivision is god-awful, so there'd be no way to fix this.
 * Make it Atari instead

Bart vs. The Space Mutants

 * Make the enemies killable by jumping on them ala Super Mario Bros.
 * Don't have The Simpsons theme play on the first stage.
 * Don't put the tilting lollipops in the mall stage.
 * Unlimited continues in case of game over.