Yes, there is an age limit for the adult Spartan events. The minimum age to race in an adult Spartan event is 15 in Croatia. The racer must be 15 years of age on race day, no exceptions are provided for anyone under 15 years of age to run the adult race on race day.
Any racers caught with underage racers on the course will be removed from the course and will not be given a refund.