Flames of Fafnir solo mode prototype play and impressions

About The Flames of Fafnir, from BoardGameGeek:

Heroes, the mighty and cunning dragon Fafnir - once a mighty nobleman, now transformed into a beast by a cursed treasure - is trying to burn our village to the ground from afar by launching fireballs from his lair in the mountains. You must answer the call and travel with the champion Sigurd through Heathland both to build defenses to protect the village and to collect runes needed to defeat the beast. Fafnir will fall to either Sigurd's sword or one of the heroes' strikes...or will he? While most heroes quest for glory in The Flames of Fafnir to receive the town's honor, one might seek victory through more nefarious means by joining Fafnir in his destruction of the village! The fireballs launched from Fafnir's mouth toward the town are represented by marbles that will collide with anything in their path, damaging heroes and destroying defenses. Each round, Fafnir acts by changing his angle of attack, spawning monsters, or building up his fiery breath. Eventually, he will release all his charged fireballs towards the town - and if all the town's walls are destroyed, everyone loses. While walking the Heathland, you'll encounter mythological creatures and monsters; slaying them will aid you in your quest as snow trolls, giant spiders, and selkies guard magical sites where ancient runes can be found. Claim these runes and bring them to bear on Fafnir to kill the dragon. You can gather wood, stone, and gold to construct defenses to protect the town. Barricades, watch towers, and trenches will reduce the carnage, and if your structures intercept the fireballs, you'll be rewarded, so plan your defense well. Praying to Gods and raising defenses will reward you with powerful artifacts that allow you to improve your movement, gain more glory, weaken the dreaded Fafnir, and more. If an opportunistic hero chooses to join Fafnir, they get to ride the dragon, turning on the other heroes thanks to rider cards while trying to destroy the town in an attempt to take victory for their self!