Overcooked is a pretty simple game. You and up to three other people are running around in a kitchen preparing food and serving it. That's pretty much it. Sound boring? Well, that's because there's more. There's caveats to every level. Perhaps the kitchen is constantly being torn in two by a powerful earthquake. Maybe you have to prepare all this food inside moving trucks that are driving back and forth. Maybe there's a huge wall in the kitchen and the only way to get food from one side to the other is to put ingredients onto a conveyor belt that wraps around the building.
At it's core, though, the difficulty in this game is purely in the efficiency with which you can make food. There are a grand total of three buttons to press: 'Pick up/Put down', 'Action', and 'Dash'. To make onion soup, all you have to do is pick up an onion, place it on the cutting board, cut it, then pick it up and put it on the pot to cook. You have to repeat that three times for that specific dish, and once the soup is done you have to put it on a plate (bowl?) before its ready to be served.
There are two things that make this game great, though. The first is the fact that everything you make requires half a dozen steps to complete, and even if those steps can each only take half a second long, they all have to be completed. Making the food can take a while, but you also have to wash plates and put out fires if you burn anything. Onion soup, the simplest of meals, takes about seven different steps to complete, ignoring the fact that you have to wash the plate-bowl when the customer is done.
The second thing about this is that the level designs are interesting and require a lot of thought and especially teamwork. The game generally works best if each person has a specific 'job' to handle, like providing people with ingredients or washing dishes. But since every level is so different you have to plan out what needs to happen every single time. Some are hard enough to require playing over and over again to achieve a score of three stars, but they are all doable.
There are a bunch of chef characters to unlock, and competitive two-on-two maps to play against your friends. The game has an upbeat "Have fun but don't be bad" feel. It can be stressful, but in my experience it isn't "loud" and doesn't give me a headache (of course, experiences with friends may vary). It's a lot of fun, and even if you and your friends play it on the couch for a few hours one or two nights, I think the game would be worth the cost of $18. Not sure you'd want to buy four copies and play online when you can play together, but I suppose that's also an option.
By the way, there's also an intense, compelling story line where you and your friends are trying to save the Onion Kingdom from 'The Beast'! There's time travel and everything! Something has fractured the kingdom and it's up to you to help. If you ask me, though, I think a lot of problems could have been solved if people didn't make horribly designed kitchens. But who am I to judge?