786.
Step 1: Dig out a parking garage underneath the store.
Step 2: They are so happy to have more parking that they give you $25,000.
Step 3: Use the money to buy a bulldozer.
Step 4: Drive the bulldozer underneath Walmart into the parking garage.
Step 5: Keep bumping into the walls/pillars.
Step 6: Earthquake Simulator 2014