Force Breaks are a gameplay mechanic that was introduced in Guilty Gear XX Λ Core.
Identical to overdrives, Force Breaks are moves that can be done at the expense of 25% Tension. Force Breaks are usually done with a specific input and then . Every character within the Λ Core entries has at least one Force Break, with each Force Break being unique to the character as well as the amount one has. For instance, there exists Force Breaks such as Baiken's Baku that can be only performed once they have enough Tension. There's also Force Breaks like like Axl's Force Break Axl Bomber that are just an enhanced version of a special move (identical to EX moves in other fighting games such as Street Fighter).
Additionally, there are Force Breaks that can only be done after inputting a special move (eg. Jam's Hyappo Shinshou) or even after doing a Force Break (eg. from Sol's Force Break Fafnir to Tyrant Rave). Some were even past moves that has now become Force Breaks (eg. Johnny's Jackhound now being only usable through Tension). A successful Force Break will be signaled with a specific sfx it causes as well as a white flash left behind the character.