High quality assets is orthogonal to fun. If you can create a fun concept with generic assets, I believe you may find an artist willing to produce the assets for you.

>High quality assets is orthogonal to fun.

Not necessarily. It's a very "programmer brain" thing to think that novel mechanics are the be-all end-all of what makes a fun game. Extremely simple games can become incredibly engaging given high quality detailed beautiful art design. Think of deck builders and board games that would be pointless with just placeholder images and spreadsheets of data, that actually become enjoyable because of the creative work that went into the assets.