Can I destroy the buildings?

Can I use humanoid character and destroy them instead?

Can I modified the geopipe model by incorporating trees wrapping the buildings as in old and abandoned city with overcrowding trees?

Hi! You are allowed to destroy buildings. Our T-Wrecks demo shows this in action.

For your second question, do you have any more details for how you might accomplish this? It might be easier to give advice with a more specific game idea.

You are allowed to modify the models however you want! Feel free to change the textures to fit your needs