Ah this is excellent - thank you so much! Game worlds have to be able to hold several different biomes or risk being repetitive and boring, so this addition is perfect for that purpose. The game I’m working on (Indigenous) allows the player to spend most of his time on a single island (or sailing around it), which means they have to be big in size and height. 
I’ll be generating my own heightmaps from World Machine to tailor to our game experience, but I have one last question/request for you:
The steep cliff shown in red here would normally be pure rock face (maybe with some tiny grass spots on the flatter areas) because of its slope angle. In most cases the color of that rock doesn’t change no matter the height, unless it’s above 1000km sea level. This is different from the alpine environment you’ve done in the past.
It looks like you’re doing this correctly because the texture looks different there than in other places on the island, but I just wanted to make sure that it’s a space I could individually edit since it’s not colored like cliff rock would be.