This ratio is heavily inflated. Don't be alarmed by it, as I only had trouble on Sparkle Island 2. Here's what I did, as I was a bit confused with other solutions.
You ONLY have to play and beat the games listed below. Only do this in party play, and make sure to save after you finish. Make sure to select easy on all of the games when possible, and make sure you beat the whole game in one session. My last game, sparkle island 2, I died on level 30(the last level). I replayed 26-30 hoping that would work, but it didn't unlock. For sparkle island 2, take your time with each level. The white bunny thing only spawns after you get rid of all the enemies, and it instantly kills you. When you begin each level, kill all but 1 enemy and wait a bit to see if any extra fruit spawns as every 10k points gives you an extra life. Try and plan to kill the last enemy near the exit. Other solutions say to ignore saving the little blue birds, but each one gives you 200 points, and I needed each and every life I had. Every other game is really easy, and most can be completed in under 10 minutes each.
Again, this is NOT a 6 ratio achievement. It is not at all difficult, and is really easy.
Autosprint 2
Bandito Chinchilla
Event Horizon II
Luftwaffe II
Sparkle Island 2
Sparkle Quest
Squadron Ace
Stunt Rider
Tank Frenzy
Trojan Frenzy
Autosprint Classic
Luftwaffe 109
Luftwaffe Turbo