In Grand Theft Auto: Vice City Stories, Giorgio Forelli attempts to kill Phil Collins due to Barry Mickelthwaite owing Giorgio Forelli money. Victor Vance kills all the hitmen squads sent therefore saving both Phil and Barry from dying.
By 1986, the Forelli family became the richest and most powerful Mafia family in Liberty City. In GTA Vice City, the Forellis had decided to expand "down south" by opening relations with local drug cartels through recently released from prison Tommy Vercetti. However, this never happened due to Sonny Forelli's death and Tommy's defection. Giorgio Forelli faces charges for fraud. The Forelli family begins to decline in power.
In GTA San Andreas, it was agreed the Forellis would own an equal share of Caligula's Palace casino in Las Venturas, along with the Sindacco and Leone families. The Families couldn't decide between themselves who should run the casino. Therefore, Ken Rosenberg was put forward as a neutral party, which any war between the families ignite, Rosenberg will be killed.
While Johnny Sindacco is at the hospital for being traumatized, the Forellis decide to take the moment to kill him, by hijacking his ambulance. Rosenberg becomes aware of the hit, and sends Carl Johnson to retrieve Johnny's ambulance before a war is ignited between the families. However, Johnny later dies from an induced heart attack, and Salvatore Leone returns to Las Venturas to reclaim the money that he invested in the casino from Rosenberg. The Forellis later send hitmen to kill Salvatore, who was aware of the hit and decides to send Carl to kill the hitmen in their flight before they arrive in Las Venturas. The hit leads to Salvatore to finish the Forellis by sending Carl to Liberty City, to kill the Forellis underboss Marco Forelli, while at the Marco's Bistro. The hit weakens the Forellis, and ends their occupation in Las Venturas, leaving the Leones to take full control of the casino.
In GTA Liberty City Stories, the Forellis deal with the death of Mayor Roger C. Hole, who was working for Franco Forelli at the time. He then had found another representative, Miles O'Donovan, to go against Donald Love, who was representing the Leone Family. However, O'Donovan wins as the voters found out that Love was unfit for office because he was working with Toni Cipriani.
Later on, a war was sparked between the Forellis and the Sindaccos in Fort Staunton, which was caused by the Sicilian Mob, after the Sindaccos had begun invading Forelli territory on Staunton Island. Toni is caught up in it, as Salvatore Leone takes advantage of the war to foil Massimo Torini's plan to take over the city. The war leads to both families to be weakened as upcoming gangs like the Uptown Yardies and the Yakuza take over their territory left behind. The families eventually try to broker a truce to which Salvatore bugs Paulie Sindacco's car to kill the Forellis attending the peace meeting. As the war continues, the Forellis continue to lose territory on Shoreside Vale, after Toni Cipriani and the Southside Hoods take over the last expanding turf the Forellis have occupation in. The war continues until Paulie Sindacco was killed after trying to flee Liberty City, after his involvement in getting Salvatore jailed.
The Forellis later target the Yakuza, after Kazuki Kasen had taken over most of the territory in Liberty City and began stocking up on powerful weapons such as a tank. The Forellis catch Kazuki's wife Toshiko Kasen attending the Fort Staunton Opera House with Toni Cipriani, and attempt to kill her (not knowing that Toshiko is against her husband's plots). The Forellis are later completely weakened after their main base of operations Fort Staunton was destroyed by underground explosives in the old subway main line running through southern Staunton Island.
In GTA III, they are named the Forelli Brothers. The Forellis seems to have been weakened considerably, with the killing of several more Forelli members. It is assumed that the Forellis have been reduced to servitude under the Leone Family and their organization on the whole is now considered a brotherhood.
A high-ranking member Mike Forelli, was killed in a car explosion by a bomb that was set by Claude, on orders from Joey Leone. Bad blood between Joey and the Forelli brothers continue, to which Joey had another Forelli killed and stuffed in a car. Due to the Forelli surveillance around the vehicle, Joey sent Claude to dispose of it at the Harwood Autocrusher and Junkyard.
El Burro also tasks Claude with killing Forellis in I Scream You Scream (as revealed by the strategy guide for Grand Theft Auto 3)
In GTA Liberty City Stories, Forelli henchmen don blue/dark red shirts with light blue/white jackets over and carry pistols. In GTA III, they dressed like the Leones as seen in one of Joey Leone's missions, although this is because they were in disguise. In GTA Vice City, the Forellis are seen wearing light blue or brown Hawaiian shirts. In GTA San Andreas, the mobsters (presumed to be the Forellis) either dress in brown jackets, light green shirts with black pants or black jogging suits. In GTA Vice City Stories, the Forelli hitman seen in a couple of missions wear dark colored shirts with black jackets over.
- The Forelli Family is the only gang to have appeared in every GTA III era game, with the exception of Grand Theft Auto Advance (although they may have appeared, as there is only a reference to the Mafia, not a particular family).
- The Forelli Family is probably the most hated gang in the GTA III era from the point of view of the protagonists. Tommy Vercetti betrayed the Forellis, Carl Johnson robbed Caligula's Palace (owned by the Forellis, Leones and Sindacco), Toni is a capo for Leone Family and therefore a natural enemy and Victor killed some Forelli hitmen, Claude kills them on Joey and El Burro's orders.
- The Forellis are the only gang to have territory in all three locations, but they end up losing it all.
- Dialog from A Date With Death suggest that the Forellis are slightly racist.