Shakuni is a very interesting character in the Mahabharata. Ved Vyasa’s Mahabharata show him as a cunning and ruthless character and part of the Chandal Chaukadi (the group of four wretches which includes Duryodhana, Dushashasan, Karna and Shakuni). He is also one of the three evil maternal uncle (mama)- other two being Kansa and Shalya.
Shakuni and his son Uluka both were ki**ed by Sahadeva on the 18th day of the war. After him, the throne of Gandhara was acquired by his other son who is not named in the text even though we do find mention of his fight with Arjuna when Arjuna went to conquer different areas for Ashvameda Yagya. Shakuni’s wife was in favour of peace and requested Arjuna to not k**l her son.
In the Jaina Mahabharata we find a story which explains why Shakuni wanted to finish the Kuru clan. This version doesn't fit with Ved Vyasa’s Mahabharata and therefore is treated as a regional retelling rather than the original version. According to this version, Bhishma was responsible for the k***ling of Gandhari’s family because they got her married to a goat and then sacrificed her to ward off evil from her (making her a widow technically) and this event was hidden from the kuru clan at the time of Gandhari's marriage to Dhritrashtra. So Bhishma invited their family and locked them in a room giving them only a morsel of grain to eat. The whole starved to d**th and Shakuni was the only one who survived. He took an oath to destroy the Kuru clan and before his d**th Shakuni’s father hit him with an iron rod making him a limp so that he never forgets his promise. It is also said that the dice he used to play were made of bones of his father's body. In Odia Mahabharata Bhishma is replaced by Duryodhana.
This story is not found in Vyasa’s Mahabharata where the family of Shakuni is mentioned to be alive during the Rajasuya sacrifice. Also his brothers were involved in the Mahabharata war.