Endurance is a game mode exclusive to Tasty Planet. It has three levels, based on Laboratory 4, Ocean 3, and Cosmos 9, respectively, all of which are losable levels, and so these levels are also losable. This is an incredibly frustrating mode where the Grey Goo grows so slowly it can take up to an hour just to beat one of the levels. Despite this, there are no checkpoints (let's be honest: there never are), but there's no time limit, either, no are there any Medals. Playing one of these levels requires beating it's Normal/Casual Mode counterpart, and beating all three of them awards the "Gravity Well" cheat.