If there was a criteria for virtual tangibility this would def get all the marks ! There's so much potential for level and puzzle making here, like high exits where you would need to pile up the corpses in a specific way to get to, different types of zombies like bigger ones which dispenses 5 times more gore, or an acidic zombie which dissolves corpses in a radius, and even exits that are blocked so you must only shoot certain zombies as not to further pile over the exit. What you have here is a very solid sandbox and a very good base to build something upon !