Design constraints are more of a creativity tool than an inconvenience. Sometimes your best ideas may come from not being able to do something and taking a simpler route instead. Games ideas often fall victim to scaling issues and a little bugger named Feature Creep, all making the game larger and larger before it's even close to finished. When I make games I start with a simple and dynamic premise that can be built on. That way once the main game is done I can add new features one at a time while having the safety of a completed game ready to go if a release deadline gets too close. Making a game when you have no idea how to implement any of the ideas is a setup for failure. Make something feasible. Something you could do at your skill level. Something you know almost every answer to. As an amateur starting on your first project ever you can't just come up with Skyrim in Space then throw it at a programmer and say "Go."