"Seeing him kill people, cutting someone's arm off ... that's not like Papa," 42-year-old Cheya Savimbi said ahead of the hearing in Nanterre, near Paris.
He and two of his siblings are asking for 100 million euros in damages from the French branch of Activision Blizzard, which makes Call of Duty, last year's best-selling video game worldwide.
But they insist that their suit is not for the money but to defend their father's reputation.
Savimbi led Unita, a Maoist-inspired guerrilla movement that fought Portuguese colonialism in Angola alongside the MPLA, which is now the ruling party.
After independence in 1975 he launched a 27-year-long civil war against the MPLA government.
With the Cold War at its height, the Soviet Union and Cuba provided political and military support to the MPLA and the US and apartheid South Africa did the same for Unita.
Savimbi, who was known to terrorise civilian politicians and was one of the first rebel leaders to finance his movement with "blood diamonds", was killed in battle in 2002 and his movement ended the fighting soon after.
Call of Duty's Black Ops II, released in 2012, portrays Savimbi on the back of a tank rallying his troops with cries of "Fight, my brothers!" and "We must finish them - death to the MPLA!".
But he is on the side of a certain Frank Woods, whom the player must free and who at one point declares, "Our dog in the fight was a guy named Jonas Savimbi."
Activision Blizzard's lawyer, Etienne Kowalski, claims that Savimbi is seen in a "rather favourable light" as a "good guy who comes to help the heroes".
The family's lawyer Carole Enfert did not agree.
Savimbi may have been a warlord but he was also "an important player in the Cold War", she said, claiming that he was a friend of Nelson Mandela and was defended "by the great men of this world", for example then US president Ronald Reagan.
The case has been covered by media in Angola, and the game has angered Unita, which is now the main opposition party.
Call of Duty, which has sold 250 million copies since it was first made in 2003, has already featured former Cuban president Fidel Castro, former US president John Kennedy and deposed Panamanian leader Manuel Noriega.
A US court rejected a suit for identity theft and diffamation brought by Noriega in 2014.