You get a crystal when your first roll of the turn is a straight with 6 dice. How does that work for a solo game that only gives you 5 dice? Pay 2 VP, get a sixth dice and then roll or does a straight with 5 dice count?
You need all 6 dice to gain the crystal for a straight. However, you can home rule it as a 5 dice straight, if you would like to make the game a tiny bit easier.