It can be pretty crazy. Using the objects objects that you collect as both ammo and a shield is the strategy to playing it.
We wrote all the systems, which included a complete voxel engine for the level generation, procedural generation, level management, and several other systems. All the SFX where created as well as several custom shaders and particle effects. We didn't use all the assets in each of the links, only a selection to make things cohesive