The six basic phases of the Software Development Life Cycle (SDLC) are requirement gathering and analysis, design, implementation (coding), testing, deployment, and maintenance. For a game development roadmap, you would begin with concept ideation and requirement specification, followed by designing the game mechanics and graphics, then coding the game features, conducting unit, integration, and system testing, deploying the game to platforms, and finally maintaining and updating it based on user feedback.
As a test case, a simple function could be:
def start_game(user_input):
if user_input == "start":
return "Game has started!"
else:
return "Please enter 'start' to play."
This function can be used to verify if the game properly responds to input, serving as a basic test for the implementation phase and throughout the SDLC.