Ngl, the art style wouldn't be really a problem as long as you are consistent with it.
Look at something like "Just Shapes and Beats", you can surely work with triangles and circles with different colors
Either as some form of a platformer with unreliable teammates, or some PvC type of game where you fight against bots and make aliances, but welp, they Will betray given the opportunity
I'd say try thinking about something fun, or something you wanted to make, bend it, twist and something will come :3
Good luck!