When you complete the first raid mission, when the ship come back then you have a mission to use the rune screen. But actually when you have finished the raid, but your ship has not returned yet, and before you get the mission, you can actually use the rune tree already, the actual raid unlocked it.

If you ever research rune before your ship return, your game become totally dead. When the ship come back, it will give the rune mission, and then detect a rune has been researched, and validate the mission, but then it will never give you the next mission, so it is game over.

And by the way all missions you already had have has been deleted as well, so your mission screen becomes void, and even as fast speed game for a while they never come back, your game is over.

The fact that a game over bug arrise in mid game is not acceptable for a "released game". This horrible game breaking bug should not even be there on a "beta version".

So I would now rank this game as "alpha stage", not released game.
What is only playable as a demo is the begining game, thats all.

It is unplayable once you reach mid game, wich do not take very long, because once you reach mid game all this features are buged to death : Missions, Heroes, rune, trade ship, bridges, villagers being stuck on roads, etc.