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

Goku Racing

 * Make it a Mario Kart 8 style go-kart racing game on Wii U.

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 any of the stages, just the title screen.
 * Don't put the tilting lollipops in the mall stage.
 * Unlimited continues in case of game over.
 * Get rid of the time limit.
 * Have Bart say "Cool man!" instead Marge saying it.

E.T.

 * Make it a Super Mario Bros style platform game on NES.

Rocko's Modern Life: Spunky's Dangerous Day

 * Have the plot be where Spunky get dognapped and Rocko has to save him.
 * Make it a beat 'em up platform game.

Mega Man X6

 * Stop the Mega Man X series after 5.

Sonic '06

 * Make the developers of this game change their minds about releasing this game in Sonic's 15th anniversary, release an remastered version of Sonic Jam instead, and delay the game to 2007 and call it Sonic Adventure 3.
 * Remove the darn glitches!

Sonic Genesis (GBA)

 * Make this game an GBA version of Sonic Jam and have all of the graphics be redone and have an Sonic Advance engine on each game in it.

Sonic Boom

 * Nothing could be done to make this game better.
 * Make this game a Star vs. The Forces of Evil-themed game and have all cameos from all Disney (including characters from non-Disney shows airing on their channels) characters in history.