Just because you can make a game, doesn't mean that you should make a game.
If you want to make a game and make a profit, then there is one central question to ask: why are you making this game?
Vanity projects are a different matter entirely. Make a game, make the game you want, and don't bend to anyone else's idea of what it should be or how you should make it. If you want to make something that will generate income, then you should probably consider some marketing basics.
Why are you making this game? Why would someone buy this game? Why would someone buy this game instead of another? Who would buy this game?
Discerning customers tend not to want to give up their valuable time to appreciate your engineering project. They will not care for the fact you only had two hours each weekend to work on your first game. Before parting with cash, customers need to see what value they are receiving.
A generic Space Invaders clone with added particle effects may make a great engineering project, might be fun to make, and might even be fun to play. But why would someone buy it?
In order to make a profitable product in a crowded marketplace, one has to consider positioning. How does this product fit into the landscape of other products? If your product does not stand above similar games or stand apart from others, then why would anyone choose it over another?
What is your game giving the player? What does your game do for them?