There are already many video game compos out there which impose different restrictions on entrants. There is Ludum Dare and the Experimental Gameplay Project, and a couple others, they can be tracked on Compo Hub
The most basic restriction which almost all compos have is theme. The hosts announce a specific theme which your game must adhere to.
Would you be interested in a Video Game Compo/Jam, where the subsequent themes would be tropes? Then you'd need to feature the declared trope prominently in your entry. The selected tropes sometimes would be video game tropes and sometimes would be generic tropes.
1. Make a game which provides example for Item Get
2. Make a game which features Deliberately Monochrome
3. Make a game which presents a Heroic BSOD
Do you like the idea? And do you like anyone would join such a compo held by a no one like me? :)
This all would be just for fun, not for profit. ;)