The Character Booster is a feature in the 2012 re-release of the Windows version of Final Fantasy VII. The Character Booster feature improves the party on a save file to give the player the opportunity to experience the game for its story without worrying about the gameplay and having to grind for levels. The feature is only available on a user's profile on the website.
The Character Booster option is found on the player's profile on their website and cannot be done offline from the launcher. In the user's main panel their most recent party will be shown, and beneath this is the "Character Booster" option. Due to cloud saving, all of a user's save files will be listed here, divided into tabs per slot, and listing a number of files. Each file is given with the play time, the location (as given in the menu), the party, the party leader's HP and MP, and the party's Gil. At the bottom of the file-display is the "Boost Characters" option.
If the player clicks the "Boost Characters" option a message warns the player of the Character Booster's functions, and tells the player the effect is not reversible. Once "Boost" is clicked, the HP, MP, and Gil on-screen go on to read "MAX". Clicking away and returning will show the player the true values of 9999, 999, and 49999999 respectively.
The game knows whether to sync the save on the game to the server, or the version on the server to the user's local saves based on the most recent timestamp. Using the Character Booster updates the timestamp, therefore, if the player saves a game in a slot and then does not sync with the server, and uses the Character Booster on that save slot on the website, the save file on the website will replace the one saved locally.
The Character Booster takes all of the members of the current party and changes their max and current HP to 9999 and MP to 999, and changes the Gil value to 49999999. Materia will still influence the party's HP and can increase or decrease it accordingly.
The Character Booster only affects a characters HP and MP, and does not affect their level or any other stats. This means enemies will still take the same amount of attacks to be defeated by a party that has used Character Booster and a party that has not. A benefit is the party will never have to worry about healing, but a drawback is that since the Limit gauge uses the percentage of HP dealt to max HP to increase, it will take far longer for players to reach their Limit Break, potentially slowing down the time a battle will take.
The Gil value will change to 49999999 when Character Booster is used. This is regardless of whether the player has a value higher than that before using it. This is not the max value, and it is likely this value was chosen over 99999999 to prevent players from getting the Master of Gil achievement.
The Character Booster can still be exploited to make it easier to get the Master of Gil achievement. The player can use Character Booster to obtain 49999999 Gil, then spend Gil on buying items and Materia from stores, and set their Gil back to 49999999 through Character Booster, and then sell the items to add some of the previously invested Gil (before using Character Booster) back onto their current Gil count.
In the original 1998 PC version of Final Fantasy VII, it is possible for the player to edit their saves. The save files are identical in the 2012 re-release, however, the cloud saving function prevents the player from being able to save the changes.
The player's save files are loaded in a folder with the user's ID, within a "FINAL FANTASY VII" folder, within a "Square Enix" folder which is found in My Documents by default. If a file has been edited and a user enters a Load/Save menu when not connected to the internet, the system will know what save file to expect and delete the file if it is not what is expected. If the file has been edited when the user is connected to the internet, the system will know save file to expect and download the proper version of the file in its place.
A player can exploit this: when in the Load menu, the game will load all the files it expects, and if at this point the player edits their save files, or introduces a new save file at the name of an old one, the player can load the new save. The save files will correct themselves the next time the player goes to Save, but if they then save the file (the one they loaded), it will be considered a valid save file and still work.
Another alternative is to disable cloud saving (in the launcher, select the "Network" tab, and uncheck cloud saving), then edit the game, launch as normal, and save at least once. Exit, and re-enable cloud saving.
As long as the player has a "valid" save (one performed by the game itself), it will use that as the most current.