Tons of bonus features and frequent payouts keep you coming back for more. Uncover golden treasures and enjoy the Rainbow Re-spin and Free Spins. . The Celtic patterns set the scene of a Great Britain of yesteryear and frame This is a game for the brave and bold! MicroGaming Online Slots. The story of. Play Celtic Courage online slot and win a pot of gold. Dive into the vibrant Irish world with Microgaming's Rainbow Burst online slot.