I need to be able to knock holes in the walls, and if the supporting walls and pillars are destroyed I want the building to collapse. This type of full building destruction would very rarely happen in the game, but if the supports are knocked out I want it to be realistic. Windows breaking and breaking through a wall with an axe or a car would be more likely.
I'd also like the terrain/ground to be destructible, kinda like http://http://tinyurl.com/776hu7e. I'd like concrete to crack, and to blow apart dirt, maybe even the ability to spear posts in the dirt. Possibly even breaking down trees? Although this would just be an extra feature, it's in no way necessary.
Havok, Physx, DMM, Geo-mod, Bullet, frostbite,and etc all have similar features to one another. I like Havok's Destruction package however the pricing will probably be above what I can pay for (I'm actually waiting for their reply). PhysX is free, but it's main feature is the graphics acceleration that requires a special graphics card which my user base probably doesn't have (I'm a little hazy on whether or not the features would work well without the acceleration). And Geomod/frostbite are not usable by indie developers. I'm unfamiliar with Bullet's capabilities.
What physics engine would work best for my destruction needs? Thanks in advance