The slaying of Rukmi by Lord Balarama is described in Srimad Bhagavatam, Harivamsa and Vishnu Purana.
This page gives a comparative study of all three texts as to how they differ in the details of the incident.
The basic story is summarised thus: On the occasion of Krsna's grandson Aniruddha's marriage to Rochana, the granddaughter of Rukmi, Rukmi organised a game of dice, and was joined by the King of Kalinga, Ashmaka, Pandya and other kingdoms. Balarama agreed to play with Rukmi, and so placing their wealth as stakes began playing.
Since Balarama was winning most of the time, Rukmi decided to cheat, and so he played deceitfully and boasted to Balarama that he won. Enraged by his deceit, Balarama lifted his mace and killed Rukmi.
The question is this: How does RUkmi's actions (cheating in the dice game) justify Balarama killing him?
There are two more famous dice games in our scriptures:
- The one between Nala and Pushkara
- The one between Kauravas and Pandavas
In both the above games too, there is a lot of deceit involved. In the first case, Pushkara cheats in the game and exiles Nala, who after learning the art of dice, returns and wins back his kingdom from Pushkara.
In the second case, Shakuni cheats to a large extent, which causes the enslaving and mistreatment of Draupadi, following which due to Draupadi's virtuosity, the Pandavas are freed, and they return to Indraprastha (after which they come back for the second game).
In both cases, the cheater is not punished with death, but is ousted in some way or the other. So how does Rukmi's deceit not grant him a punishment similar to the above two cases, but instead amounts to his death?