Try to make a serious game - and if you're unable to, pretend that you meant to make a joke game! Finishing something is better than finishing nothing.
Just out of curiosity, what do you mean by "joke game?" I ask because I very frequently put stuff in my games that I find funny, or is somewhat lowbrow / toilet humor. No reason you can't have fun making a game. Games like Conker's Bad Fur day were made to not be "serious" and are still great games 25 years later.
