The earn the good ending in Oddworld: Soulstorm, you need to score a
majority of Good Quarma ranks for each level. You’ll be able to see your Quarma in the Level Select menu under each level, you’ll see a red or blue icon. A red icon signifies Bad Quarma, and a blue icon signifies Good Quarma. It’s okay to get several Bad Quarma ranks you don’t need all Good Quarma to get the best ending.
I was able to get the Good Ending with three Bad Quarma ranks. So, you absolutely don’t need to replay every level to get Good Quarma. To get Good Quarma, you mostly need to