Sláine: The Roleplaying Game of Celtic Heroes is a fantasy role-playing game (RPG) designed by Ian Sturrock, and first published in 2002 by Mongoose Publishing. The game is currently out of print. It was derived from Sláine using the d20 System.
Mongoose's second RPG, Sláine, The Roleplaying Game of Celtic Fantasy (2002), was based on another 2000AD license like the company's first RPG, The Judge Dredd Roleplaying Game. Both of these RPGs used the d20 System although Sláine differentiated itself from other fantasy systems with some new concepts, such as "enech" — a sort of reputation and honor system. Mongoose was able to support all four of their d20 RPGs throughout the d20 boom. They had already learned how to support RPGs quickly and constantly through their work on d20 fantasy books; now they applied those rules to their in-house releases, and as a result Sláine received 10 supplements (2002-2003). The d20 boom turned into a d20 bust starting in 2003, and Sláine ended its run in that year.
Mongoose published a RuneQuest edition of Sláine (2007), though it was not well-supported.
The setting itself is closely based on the 2000 AD comic series Sláine, created by Pat Mills & Angie Kincaid, but is also drawn heavily from Celtic mythology. In Tir Nan Og, The Land of the Young, dwell the four tribes who worship Danu. They are a freedom-loving people and regard leadership a mere step away from totalitarianism. This freedom of course includes the right to fight, feast, and raid their neighbours. The four tribes are The Sessair, The Fir Domain, The Finians and the Falians. In their centre is Dinas Emrys the eternal fortress, the repository of druidic knowledge and the home of the ever-living ones.
On all their borders they are beset by troubles, south of them the Drune lords, whose religion is a perversion of their own, preach that death is the only end to suffering in this life, and that death should be brought to all as a blessing. To the west the berserkers dwell, who delight in raiding and violence as much as the Tribes of the Earth Goddess. To the north the fomorians live, sea-demons, strange chimerae of man and beast who eat the suffering of mortals and drink their tears. Beneath the earth, the El-Worlds consist of strange reflections of earth, where the gods themselves rule kingdoms.