There was a Japanese company in the 90s called Spec Computer that tried doing that with PSX cards. One of their cards was for Tokimeki Memorial. It had save files with various stats hacked to 999, and a few right before some of game's harder to get endings. Spec Computer ended up getting sued by Konami.

The irony of this is that Tokimeki Memorial has a cheat code for getting 999 in all stats. You activate it by naming yourself ×.