Made by developers of titles like Dragon Age, the RPG The Waylanders, currently in early access, is set to take players on a magical journey through time and space, in a land and culture inspired heavily by Celtic Mythology. A good portion of the characters and visuals in this party-based roleplaying game seem to be directly inspired by written s of Celtic culture and myths and the way these old stories were often distorted by the biases of medieval scholars and Christian theologians.
Some of the developers behind The Waylanders had previously worked on the bestselling RPG Pillars of Eternity; fittingly enough, the plot of The Waylanders explores themes of past-lives and reincarnation much as Pillars of Eternity did. The main character, a player-created protagonist, is caught in the middle of a magical disaster during a meeting between a group of mortal Celts and their deities, the Tuatha De Danann. The protagonist loses their ability to reincarnate, but in exchange, gains the ability to travel back and forth in time between their magical era and a more mundane future of Medieval Christianity. To save their world from destruction, they must overcome great challenges with both their present-day companions and their future reincarnations.
A caveat: the historical Celts weren't some monolithic empire or unified nation. The Celtic people were a mass of different tribes that spread in a massive diaspora across the European continent, united by a shared cultural mythos, religious practices, and stylistic motifs in various artifacts recovered by archaeologists – leaf-bladed swords, metalworks with knots and spirals, and the infamous torc necklace. Nearly all the written sources about the Celts were written by non-Celts, or scholars from Christianized Celtic cultures like Ireland who tried to awkwardly fit their old stories into the framework of The Bible. This conflict between original pagan mythology and Christian revisionism in the primary sources listed below seems to have inspired a large portion of the time travel plot in The Waylanders.
The Book of Invasions & The Tuatha De Danann
The Lebor Gabála Érenn, colloquially translated to The Book of Invasions, is a tangled collection of Old Irish poems and prose stories compiled in the 11th century. The Christian author presents their text as a history of Ireland and the various peoples who migrated there, but when you strip away the references to Noah's Flood and the Illiad, what remains are epic sagas about Ireland's ancient pantheon of gods – the Tuatha de Danann and their ancient enemies the Fomorians. Key characters of this book include Nuada, the silver-armed king of the Tuatha, and the Sun God Lugh, prophesied to kill his grandfather Balor, a Fomorian lord with a laser-shooting eye of death.
The Tain
In the Táin Bó Cúailnge, which roughly translates to "The Cattle Raid of Cooley," Queen Maeve of Connacht tries to seize a fancy-looking cow from the nation of Ulster and brings a vast army with her to get the jobs done. With the warriors of Ulster incapacitated by an ill-timed curse, the only warrior who can defy the armies of Connacht is a 17-year old warrior named Cú Chulainn, armed with a wickedly cruel spears called the Gae Bolg and the ability to warp himself into a hug, unstoppable rage monster (think the Hulk, but with his body constantly in danger of tearing itself apart).
Fiann Mac Cumhaill And the Fenian Cycle
Britain and Wales might have the legend of King Arthur and his Knights of the Round Table, but Ireland has the Fenian Cycle, which tells the story Fiann Mac Cumhail, a wise warrior-king who leads a company of heroes called the Fianna. Fiann, skilled with both weapons and magic, gained great Insight through eating the Salmon of Wisdom, then gained leadership over the Fianna by defeating the wicked Faerie lord Aodh. Like King Arthur and Charlemagne, he's said to be sleeping under a mountain, to reawaken in Ireland's greatest hour of need.
Commentaries On the Gallic War, Written By Julius Caesar
Before becoming Dictator of Rome and getting stabbed on the Senate floor, Julius Caesar built his reputation campaigning in Gaul, subjugating the Celtic nations there and launching a brief invasion of Britain. To boost his reputation back in the Roman Republic, he wrote an autobiographical called Commentāriī dē Bellō Gallicō (Commentaries On the Gallic War), which played up his military accomplishments for readers back home and described the culture of the peoples he conquered.
Caesar was very keen on both self-aggrandizement and playing up the savagery of his Gallic opponents in order to flatter the people of 'civilized' Rome. Despite that, Caesar's clear, direct prose makes his work both a valuable resource for Latin students and historians able to read between the lines. Albeit through a Roman lens, Caesar's commentaries contain valuable details on the Celtic pantheon of deities, along with their religious practices, war tactics, and social class of priests, healers, oracles, and storytellers known as the Druids.