Test Strategy - Which test design methods to be used at every level of software development according to V-model?

I have to write a test strategy, which should specify test design methods for every test level according to V-model. The application which needs to be tested is a Tic-tac-toe game,which is a Windows form application in C#. The four test levels are component,integration, system and acceptance testing. For component testing - whitebox (Statement coverage) method will be used. For integration testing - Top down integration stratergy will be used. For system and acceptance testing which test design method do I need to use? whether it is blackbox or whitebox or what strategy to be considered?. Please provide some suggestions. Thanks!!