If there was a mode, for example, that caused enemy bullets to instead cause weight gain but then changed immobility to a fail state, the mechanics would be completely flipped on their head. Being forced to dodge every single thing on the screen to avoid getting fat would be really challenging, but I think it would be a really fun change of pace. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.